[Why]
The sequence for collecting down_reply from source perspective should
be:
Request_n->repeat (get partial reply of Request_n->clear message ready
flag to ack DPRX that the message is received) till all partial
replies for Request_n are received->new Request_n+1.
Now there is chance that drm_dp_mst_hpd_irq() will fire new down
request in the tx queue when the down reply is incomplete. Source is
restricted to generate interveleaved message transactions so we should
avoid it.
Also, while assembling partial reply packets, reading out DPCD DOWN_REP
Sideband MSG buffer + clearing DOWN_REP_MSG_RDY flag should be
wrapped up as a complete operation for reading out a reply packet.
Kicking off a new request before clearing DOWN_REP_MSG_RDY flag might
be risky. e.g. If the reply of the new request has overwritten the
DPRX DOWN_REP Sideband MSG buffer before source writing one to clear
DOWN_REP_MSG_RDY flag, source then unintentionally flushes the reply
for the new request. Should handle the up request in the same way.
[How]
Separete drm_dp_mst_hpd_irq() into 2 steps. After acking the MST IRQ
event, driver calls drm_dp_mst_hpd_irq_send_new_request() and might
trigger drm_dp_mst_kick_tx() only when there is no on going message
transaction.
Changes since v1:
* Reworked on review comments received
-> Adjust the fix to let driver explicitly kick off new down request
when mst irq event is handled and acked
-> Adjust the commit message
Changes since v2:
* Adjust the commit message
* Adjust the naming of the divided 2 functions and add a new input
parameter "ack".
* Adjust code flow as per review comments.
Signed-off-by: Wayne Lin <Wayne.Lin(a)amd.com>
Cc: stable(a)vger.kernel.org
---
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 33 +++++++++-------
drivers/gpu/drm/display/drm_dp_mst_topology.c | 39 +++++++++++++++++--
drivers/gpu/drm/i915/display/intel_dp.c | 7 ++--
drivers/gpu/drm/nouveau/dispnv50/disp.c | 12 ++++--
include/drm/display/drm_dp_mst_helper.h | 7 +++-
5 files changed, 70 insertions(+), 28 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index d5cec03eaa8d..597c3368bcfb 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -3236,6 +3236,7 @@ static void dm_handle_mst_sideband_msg(struct amdgpu_dm_connector *aconnector)
{
u8 esi[DP_PSR_ERROR_STATUS - DP_SINK_COUNT_ESI] = { 0 };
u8 dret;
+ u8 ack;
bool new_irq_handled = false;
int dpcd_addr;
int dpcd_bytes_to_read;
@@ -3265,34 +3266,36 @@ static void dm_handle_mst_sideband_msg(struct amdgpu_dm_connector *aconnector)
process_count < max_process_count) {
u8 retry;
dret = 0;
+ ack = 0;
process_count++;
DRM_DEBUG_DRIVER("ESI %02x %02x %02x\n", esi[0], esi[1], esi[2]);
/* handle HPD short pulse irq */
if (aconnector->mst_mgr.mst_state)
- drm_dp_mst_hpd_irq(
- &aconnector->mst_mgr,
- esi,
- &new_irq_handled);
+ drm_dp_mst_hpd_irq_handle_event(&aconnector->mst_mgr,
+ esi,
+ &ack,
+ &new_irq_handled);
if (new_irq_handled) {
/* ACK at DPCD to notify down stream */
- const int ack_dpcd_bytes_to_write =
- dpcd_bytes_to_read - 1;
-
for (retry = 0; retry < 3; retry++) {
- u8 wret;
-
- wret = drm_dp_dpcd_write(
- &aconnector->dm_dp_aux.aux,
- dpcd_addr + 1,
- &esi[1],
- ack_dpcd_bytes_to_write);
- if (wret == ack_dpcd_bytes_to_write)
+ ssize_t wret;
+
+ wret = drm_dp_dpcd_writeb(&aconnector->dm_dp_aux.aux,
+ dpcd_addr + 1,
+ ack);
+ if (wret == 1)
break;
}
+ if (retry == 3) {
+ DRM_ERROR("Failed to ack MST event.\n");
+ return;
+ }
+
+ drm_dp_mst_hpd_irq_send_new_request(&aconnector->mst_mgr);
/* check if there is new irq to be handled */
dret = drm_dp_dpcd_read(
&aconnector->dm_dp_aux.aux,
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 38dab76ae69e..13165e764709 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -4053,9 +4053,10 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
}
/**
- * drm_dp_mst_hpd_irq() - MST hotplug IRQ notify
+ * drm_dp_mst_hpd_irq_handle_event() - MST hotplug IRQ handle MST event
* @mgr: manager to notify irq for.
* @esi: 4 bytes from SINK_COUNT_ESI
+ * @ack: flags of events to ack
* @handled: whether the hpd interrupt was consumed or not
*
* This should be called from the driver when it detects a short IRQ,
@@ -4063,7 +4064,8 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
* topology manager will process the sideband messages received as a result
* of this.
*/
-int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled)
+int drm_dp_mst_hpd_irq_handle_event(struct drm_dp_mst_topology_mgr *mgr, const u8 *esi,
+ u8 *ack, bool *handled)
{
int ret = 0;
int sc;
@@ -4078,18 +4080,47 @@ int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handl
if (esi[1] & DP_DOWN_REP_MSG_RDY) {
ret = drm_dp_mst_handle_down_rep(mgr);
*handled = true;
+ *ack |= DP_DOWN_REP_MSG_RDY;
}
if (esi[1] & DP_UP_REQ_MSG_RDY) {
ret |= drm_dp_mst_handle_up_req(mgr);
*handled = true;
+ *ack |= DP_UP_REQ_MSG_RDY;
}
- drm_dp_mst_kick_tx(mgr);
return ret;
}
-EXPORT_SYMBOL(drm_dp_mst_hpd_irq);
+EXPORT_SYMBOL(drm_dp_mst_hpd_irq_handle_event);
+
+/**
+ * drm_dp_mst_hpd_irq_send_new_request() - MST hotplug IRQ kick off new request
+ * @mgr: manager to notify irq for.
+ *
+ * This should be called from the driver when mst irq event is handled
+ * and acked. Note that new down request should only be sent when
+ * previous message transaction is completed. Source is not supposed to generate
+ * interleaved message transactions.
+ */
+void drm_dp_mst_hpd_irq_send_new_request(struct drm_dp_mst_topology_mgr *mgr)
+{
+ struct drm_dp_sideband_msg_tx *txmsg;
+ bool kick = true;
+ mutex_lock(&mgr->qlock);
+ txmsg = list_first_entry_or_null(&mgr->tx_msg_downq,
+ struct drm_dp_sideband_msg_tx, next);
+ /* If last transaction is not completed yet*/
+ if (!txmsg ||
+ txmsg->state == DRM_DP_SIDEBAND_TX_START_SEND ||
+ txmsg->state == DRM_DP_SIDEBAND_TX_SENT)
+ kick = false;
+ mutex_unlock(&mgr->qlock);
+
+ if (kick)
+ drm_dp_mst_kick_tx(mgr);
+}
+EXPORT_SYMBOL(drm_dp_mst_hpd_irq_send_new_request);
/**
* drm_dp_mst_detect_port() - get connection status for an MST port
* @connector: DRM connector for this port
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 4bec8cd7979f..f24602887015 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4062,9 +4062,7 @@ intel_dp_mst_hpd_irq(struct intel_dp *intel_dp, u8 *esi, u8 *ack)
{
bool handled = false;
- drm_dp_mst_hpd_irq(&intel_dp->mst_mgr, esi, &handled);
- if (handled)
- ack[1] |= esi[1] & (DP_DOWN_REP_MSG_RDY | DP_UP_REQ_MSG_RDY);
+ drm_dp_mst_hpd_irq_handle_event(&intel_dp->mst_mgr, esi, &ack[1], &handled);
if (esi[1] & DP_CP_IRQ) {
intel_hdcp_handle_cp_irq(intel_dp->attached_connector);
@@ -4139,6 +4137,9 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
if (!intel_dp_ack_sink_irq_esi(intel_dp, ack))
drm_dbg_kms(&i915->drm, "Failed to ack ESI\n");
+
+ if (ack[1] & (DP_DOWN_REP_MSG_RDY | DP_UP_REQ_MSG_RDY))
+ drm_dp_mst_hpd_irq_send_new_request(&intel_dp->mst_mgr);
}
return link_ok;
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 9b6824f6b9e4..b2d9978e88a8 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1357,6 +1357,7 @@ nv50_mstm_service(struct nouveau_drm *drm,
bool handled = true, ret = true;
int rc;
u8 esi[8] = {};
+ u8 ack;
while (handled) {
rc = drm_dp_dpcd_read(aux, DP_SINK_COUNT_ESI, esi, 8);
@@ -1365,16 +1366,19 @@ nv50_mstm_service(struct nouveau_drm *drm,
break;
}
- drm_dp_mst_hpd_irq(&mstm->mgr, esi, &handled);
+ ack = 0;
+ drm_dp_mst_hpd_irq_handle_event(&mstm->mgr, esi, &ack, &handled);
if (!handled)
break;
- rc = drm_dp_dpcd_write(aux, DP_SINK_COUNT_ESI + 1, &esi[1],
- 3);
- if (rc != 3) {
+ rc = drm_dp_dpcd_writeb(aux, DP_SINK_COUNT_ESI + 1, ack);
+
+ if (rc != 1) {
ret = false;
break;
}
+
+ drm_dp_mst_hpd_irq_send_new_request(&mstm->mgr);
}
if (!ret)
diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
index 32c764fb9cb5..40e855c8407c 100644
--- a/include/drm/display/drm_dp_mst_helper.h
+++ b/include/drm/display/drm_dp_mst_helper.h
@@ -815,8 +815,11 @@ void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr);
bool drm_dp_read_mst_cap(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state);
-int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled);
-
+int drm_dp_mst_hpd_irq_handle_event(struct drm_dp_mst_topology_mgr *mgr,
+ const u8 *esi,
+ u8 *ack,
+ bool *handled);
+void drm_dp_mst_hpd_irq_send_new_request(struct drm_dp_mst_topology_mgr *mgr);
int
drm_dp_mst_detect_port(struct drm_connector *connector,
--
2.37.3
The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x be37bed754ed90b2655382f93f9724b3c1aae847
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023060713-slogan-lucrative-b623@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From be37bed754ed90b2655382f93f9724b3c1aae847 Mon Sep 17 00:00:00 2001
From: Mirsad Goran Todorovac <mirsad.todorovac(a)alu.unizg.hr>
Date: Tue, 9 May 2023 10:47:47 +0200
Subject: [PATCH] test_firmware: fix a memory leak with reqs buffer
Dan Carpenter spotted that test_fw_config->reqs will be leaked if
trigger_batched_requests_store() is called two or more times.
The same appears with trigger_batched_requests_async_store().
This bug wasn't trigger by the tests, but observed by Dan's visual
inspection of the code.
The recommended workaround was to return -EBUSY if test_fw_config->reqs
is already allocated.
Fixes: 7feebfa487b92 ("test_firmware: add support for request_firmware_into_buf")
Cc: Luis Chamberlain <mcgrof(a)kernel.org>
Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Cc: Russ Weight <russell.h.weight(a)intel.com>
Cc: Tianfei Zhang <tianfei.zhang(a)intel.com>
Cc: Shuah Khan <shuah(a)kernel.org>
Cc: Colin Ian King <colin.i.king(a)gmail.com>
Cc: Randy Dunlap <rdunlap(a)infradead.org>
Cc: linux-kselftest(a)vger.kernel.org
Cc: stable(a)vger.kernel.org # v5.4
Suggested-by: Dan Carpenter <error27(a)gmail.com>
Suggested-by: Takashi Iwai <tiwai(a)suse.de>
Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac(a)alu.unizg.hr>
Reviewed-by: Dan Carpenter <dan.carpenter(a)linaro.org>
Acked-by: Luis Chamberlain <mcgrof(a)kernel.org>
Link: https://lore.kernel.org/r/20230509084746.48259-2-mirsad.todorovac@alu.unizg…
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index 35417e0af3f4..91b232ed3161 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -913,6 +913,11 @@ static ssize_t trigger_batched_requests_store(struct device *dev,
mutex_lock(&test_fw_mutex);
+ if (test_fw_config->reqs) {
+ rc = -EBUSY;
+ goto out_bail;
+ }
+
test_fw_config->reqs =
vzalloc(array3_size(sizeof(struct test_batched_req),
test_fw_config->num_requests, 2));
@@ -1011,6 +1016,11 @@ ssize_t trigger_batched_requests_async_store(struct device *dev,
mutex_lock(&test_fw_mutex);
+ if (test_fw_config->reqs) {
+ rc = -EBUSY;
+ goto out_bail;
+ }
+
test_fw_config->reqs =
vzalloc(array3_size(sizeof(struct test_batched_req),
test_fw_config->num_requests, 2));
The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x be37bed754ed90b2655382f93f9724b3c1aae847
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023060712-bounding-unlinked-5f90@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From be37bed754ed90b2655382f93f9724b3c1aae847 Mon Sep 17 00:00:00 2001
From: Mirsad Goran Todorovac <mirsad.todorovac(a)alu.unizg.hr>
Date: Tue, 9 May 2023 10:47:47 +0200
Subject: [PATCH] test_firmware: fix a memory leak with reqs buffer
Dan Carpenter spotted that test_fw_config->reqs will be leaked if
trigger_batched_requests_store() is called two or more times.
The same appears with trigger_batched_requests_async_store().
This bug wasn't trigger by the tests, but observed by Dan's visual
inspection of the code.
The recommended workaround was to return -EBUSY if test_fw_config->reqs
is already allocated.
Fixes: 7feebfa487b92 ("test_firmware: add support for request_firmware_into_buf")
Cc: Luis Chamberlain <mcgrof(a)kernel.org>
Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Cc: Russ Weight <russell.h.weight(a)intel.com>
Cc: Tianfei Zhang <tianfei.zhang(a)intel.com>
Cc: Shuah Khan <shuah(a)kernel.org>
Cc: Colin Ian King <colin.i.king(a)gmail.com>
Cc: Randy Dunlap <rdunlap(a)infradead.org>
Cc: linux-kselftest(a)vger.kernel.org
Cc: stable(a)vger.kernel.org # v5.4
Suggested-by: Dan Carpenter <error27(a)gmail.com>
Suggested-by: Takashi Iwai <tiwai(a)suse.de>
Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac(a)alu.unizg.hr>
Reviewed-by: Dan Carpenter <dan.carpenter(a)linaro.org>
Acked-by: Luis Chamberlain <mcgrof(a)kernel.org>
Link: https://lore.kernel.org/r/20230509084746.48259-2-mirsad.todorovac@alu.unizg…
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index 35417e0af3f4..91b232ed3161 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -913,6 +913,11 @@ static ssize_t trigger_batched_requests_store(struct device *dev,
mutex_lock(&test_fw_mutex);
+ if (test_fw_config->reqs) {
+ rc = -EBUSY;
+ goto out_bail;
+ }
+
test_fw_config->reqs =
vzalloc(array3_size(sizeof(struct test_batched_req),
test_fw_config->num_requests, 2));
@@ -1011,6 +1016,11 @@ ssize_t trigger_batched_requests_async_store(struct device *dev,
mutex_lock(&test_fw_mutex);
+ if (test_fw_config->reqs) {
+ rc = -EBUSY;
+ goto out_bail;
+ }
+
test_fw_config->reqs =
vzalloc(array3_size(sizeof(struct test_batched_req),
test_fw_config->num_requests, 2));
The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x be37bed754ed90b2655382f93f9724b3c1aae847
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023060711-daybed-acting-a047@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From be37bed754ed90b2655382f93f9724b3c1aae847 Mon Sep 17 00:00:00 2001
From: Mirsad Goran Todorovac <mirsad.todorovac(a)alu.unizg.hr>
Date: Tue, 9 May 2023 10:47:47 +0200
Subject: [PATCH] test_firmware: fix a memory leak with reqs buffer
Dan Carpenter spotted that test_fw_config->reqs will be leaked if
trigger_batched_requests_store() is called two or more times.
The same appears with trigger_batched_requests_async_store().
This bug wasn't trigger by the tests, but observed by Dan's visual
inspection of the code.
The recommended workaround was to return -EBUSY if test_fw_config->reqs
is already allocated.
Fixes: 7feebfa487b92 ("test_firmware: add support for request_firmware_into_buf")
Cc: Luis Chamberlain <mcgrof(a)kernel.org>
Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Cc: Russ Weight <russell.h.weight(a)intel.com>
Cc: Tianfei Zhang <tianfei.zhang(a)intel.com>
Cc: Shuah Khan <shuah(a)kernel.org>
Cc: Colin Ian King <colin.i.king(a)gmail.com>
Cc: Randy Dunlap <rdunlap(a)infradead.org>
Cc: linux-kselftest(a)vger.kernel.org
Cc: stable(a)vger.kernel.org # v5.4
Suggested-by: Dan Carpenter <error27(a)gmail.com>
Suggested-by: Takashi Iwai <tiwai(a)suse.de>
Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac(a)alu.unizg.hr>
Reviewed-by: Dan Carpenter <dan.carpenter(a)linaro.org>
Acked-by: Luis Chamberlain <mcgrof(a)kernel.org>
Link: https://lore.kernel.org/r/20230509084746.48259-2-mirsad.todorovac@alu.unizg…
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index 35417e0af3f4..91b232ed3161 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -913,6 +913,11 @@ static ssize_t trigger_batched_requests_store(struct device *dev,
mutex_lock(&test_fw_mutex);
+ if (test_fw_config->reqs) {
+ rc = -EBUSY;
+ goto out_bail;
+ }
+
test_fw_config->reqs =
vzalloc(array3_size(sizeof(struct test_batched_req),
test_fw_config->num_requests, 2));
@@ -1011,6 +1016,11 @@ ssize_t trigger_batched_requests_async_store(struct device *dev,
mutex_lock(&test_fw_mutex);
+ if (test_fw_config->reqs) {
+ rc = -EBUSY;
+ goto out_bail;
+ }
+
test_fw_config->reqs =
vzalloc(array3_size(sizeof(struct test_batched_req),
test_fw_config->num_requests, 2));
The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x 4acfe3dfde685a5a9eaec5555351918e2d7266a1
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023060759-knapsack-prior-7f86@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 4acfe3dfde685a5a9eaec5555351918e2d7266a1 Mon Sep 17 00:00:00 2001
From: Mirsad Goran Todorovac <mirsad.todorovac(a)alu.unizg.hr>
Date: Tue, 9 May 2023 10:47:45 +0200
Subject: [PATCH] test_firmware: prevent race conditions by a correct
implementation of locking
Dan Carpenter spotted a race condition in a couple of situations like
these in the test_firmware driver:
static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
{
u8 val;
int ret;
ret = kstrtou8(buf, 10, &val);
if (ret)
return ret;
mutex_lock(&test_fw_mutex);
*(u8 *)cfg = val;
mutex_unlock(&test_fw_mutex);
/* Always return full write size even if we didn't consume all */
return size;
}
static ssize_t config_num_requests_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
int rc;
mutex_lock(&test_fw_mutex);
if (test_fw_config->reqs) {
pr_err("Must call release_all_firmware prior to changing config\n");
rc = -EINVAL;
mutex_unlock(&test_fw_mutex);
goto out;
}
mutex_unlock(&test_fw_mutex);
rc = test_dev_config_update_u8(buf, count,
&test_fw_config->num_requests);
out:
return rc;
}
static ssize_t config_read_fw_idx_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
return test_dev_config_update_u8(buf, count,
&test_fw_config->read_fw_idx);
}
The function test_dev_config_update_u8() is called from both the locked
and the unlocked context, function config_num_requests_store() and
config_read_fw_idx_store() which can both be called asynchronously as
they are driver's methods, while test_dev_config_update_u8() and siblings
change their argument pointed to by u8 *cfg or similar pointer.
To avoid deadlock on test_fw_mutex, the lock is dropped before calling
test_dev_config_update_u8() and re-acquired within test_dev_config_update_u8()
itself, but alas this creates a race condition.
Having two locks wouldn't assure a race-proof mutual exclusion.
This situation is best avoided by the introduction of a new, unlocked
function __test_dev_config_update_u8() which can be called from the locked
context and reducing test_dev_config_update_u8() to:
static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
{
int ret;
mutex_lock(&test_fw_mutex);
ret = __test_dev_config_update_u8(buf, size, cfg);
mutex_unlock(&test_fw_mutex);
return ret;
}
doing the locking and calling the unlocked primitive, which enables both
locked and unlocked versions without duplication of code.
The similar approach was applied to all functions called from the locked
and the unlocked context, which safely mitigates both deadlocks and race
conditions in the driver.
__test_dev_config_update_bool(), __test_dev_config_update_u8() and
__test_dev_config_update_size_t() unlocked versions of the functions
were introduced to be called from the locked contexts as a workaround
without releasing the main driver's lock and thereof causing a race
condition.
The test_dev_config_update_bool(), test_dev_config_update_u8() and
test_dev_config_update_size_t() locked versions of the functions
are being called from driver methods without the unnecessary multiplying
of the locking and unlocking code for each method, and complicating
the code with saving of the return value across lock.
Fixes: 7feebfa487b92 ("test_firmware: add support for request_firmware_into_buf")
Cc: Luis Chamberlain <mcgrof(a)kernel.org>
Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Cc: Russ Weight <russell.h.weight(a)intel.com>
Cc: Takashi Iwai <tiwai(a)suse.de>
Cc: Tianfei Zhang <tianfei.zhang(a)intel.com>
Cc: Shuah Khan <shuah(a)kernel.org>
Cc: Colin Ian King <colin.i.king(a)gmail.com>
Cc: Randy Dunlap <rdunlap(a)infradead.org>
Cc: linux-kselftest(a)vger.kernel.org
Cc: stable(a)vger.kernel.org # v5.4
Suggested-by: Dan Carpenter <error27(a)gmail.com>
Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac(a)alu.unizg.hr>
Link: https://lore.kernel.org/r/20230509084746.48259-1-mirsad.todorovac@alu.unizg…
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index 05ed84c2fc4c..35417e0af3f4 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -353,16 +353,26 @@ static ssize_t config_test_show_str(char *dst,
return len;
}
+static inline int __test_dev_config_update_bool(const char *buf, size_t size,
+ bool *cfg)
+{
+ int ret;
+
+ if (kstrtobool(buf, cfg) < 0)
+ ret = -EINVAL;
+ else
+ ret = size;
+
+ return ret;
+}
+
static int test_dev_config_update_bool(const char *buf, size_t size,
bool *cfg)
{
int ret;
mutex_lock(&test_fw_mutex);
- if (kstrtobool(buf, cfg) < 0)
- ret = -EINVAL;
- else
- ret = size;
+ ret = __test_dev_config_update_bool(buf, size, cfg);
mutex_unlock(&test_fw_mutex);
return ret;
@@ -373,7 +383,8 @@ static ssize_t test_dev_config_show_bool(char *buf, bool val)
return snprintf(buf, PAGE_SIZE, "%d\n", val);
}
-static int test_dev_config_update_size_t(const char *buf,
+static int __test_dev_config_update_size_t(
+ const char *buf,
size_t size,
size_t *cfg)
{
@@ -384,9 +395,7 @@ static int test_dev_config_update_size_t(const char *buf,
if (ret)
return ret;
- mutex_lock(&test_fw_mutex);
*(size_t *)cfg = new;
- mutex_unlock(&test_fw_mutex);
/* Always return full write size even if we didn't consume all */
return size;
@@ -402,7 +411,7 @@ static ssize_t test_dev_config_show_int(char *buf, int val)
return snprintf(buf, PAGE_SIZE, "%d\n", val);
}
-static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
+static int __test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
{
u8 val;
int ret;
@@ -411,14 +420,23 @@ static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
if (ret)
return ret;
- mutex_lock(&test_fw_mutex);
*(u8 *)cfg = val;
- mutex_unlock(&test_fw_mutex);
/* Always return full write size even if we didn't consume all */
return size;
}
+static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
+{
+ int ret;
+
+ mutex_lock(&test_fw_mutex);
+ ret = __test_dev_config_update_u8(buf, size, cfg);
+ mutex_unlock(&test_fw_mutex);
+
+ return ret;
+}
+
static ssize_t test_dev_config_show_u8(char *buf, u8 val)
{
return snprintf(buf, PAGE_SIZE, "%u\n", val);
@@ -471,10 +489,10 @@ static ssize_t config_num_requests_store(struct device *dev,
mutex_unlock(&test_fw_mutex);
goto out;
}
- mutex_unlock(&test_fw_mutex);
- rc = test_dev_config_update_u8(buf, count,
- &test_fw_config->num_requests);
+ rc = __test_dev_config_update_u8(buf, count,
+ &test_fw_config->num_requests);
+ mutex_unlock(&test_fw_mutex);
out:
return rc;
@@ -518,10 +536,10 @@ static ssize_t config_buf_size_store(struct device *dev,
mutex_unlock(&test_fw_mutex);
goto out;
}
- mutex_unlock(&test_fw_mutex);
- rc = test_dev_config_update_size_t(buf, count,
- &test_fw_config->buf_size);
+ rc = __test_dev_config_update_size_t(buf, count,
+ &test_fw_config->buf_size);
+ mutex_unlock(&test_fw_mutex);
out:
return rc;
@@ -548,10 +566,10 @@ static ssize_t config_file_offset_store(struct device *dev,
mutex_unlock(&test_fw_mutex);
goto out;
}
- mutex_unlock(&test_fw_mutex);
- rc = test_dev_config_update_size_t(buf, count,
- &test_fw_config->file_offset);
+ rc = __test_dev_config_update_size_t(buf, count,
+ &test_fw_config->file_offset);
+ mutex_unlock(&test_fw_mutex);
out:
return rc;
The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 4acfe3dfde685a5a9eaec5555351918e2d7266a1
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023060756-uncivil-lagged-33b5@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 4acfe3dfde685a5a9eaec5555351918e2d7266a1 Mon Sep 17 00:00:00 2001
From: Mirsad Goran Todorovac <mirsad.todorovac(a)alu.unizg.hr>
Date: Tue, 9 May 2023 10:47:45 +0200
Subject: [PATCH] test_firmware: prevent race conditions by a correct
implementation of locking
Dan Carpenter spotted a race condition in a couple of situations like
these in the test_firmware driver:
static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
{
u8 val;
int ret;
ret = kstrtou8(buf, 10, &val);
if (ret)
return ret;
mutex_lock(&test_fw_mutex);
*(u8 *)cfg = val;
mutex_unlock(&test_fw_mutex);
/* Always return full write size even if we didn't consume all */
return size;
}
static ssize_t config_num_requests_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
int rc;
mutex_lock(&test_fw_mutex);
if (test_fw_config->reqs) {
pr_err("Must call release_all_firmware prior to changing config\n");
rc = -EINVAL;
mutex_unlock(&test_fw_mutex);
goto out;
}
mutex_unlock(&test_fw_mutex);
rc = test_dev_config_update_u8(buf, count,
&test_fw_config->num_requests);
out:
return rc;
}
static ssize_t config_read_fw_idx_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
return test_dev_config_update_u8(buf, count,
&test_fw_config->read_fw_idx);
}
The function test_dev_config_update_u8() is called from both the locked
and the unlocked context, function config_num_requests_store() and
config_read_fw_idx_store() which can both be called asynchronously as
they are driver's methods, while test_dev_config_update_u8() and siblings
change their argument pointed to by u8 *cfg or similar pointer.
To avoid deadlock on test_fw_mutex, the lock is dropped before calling
test_dev_config_update_u8() and re-acquired within test_dev_config_update_u8()
itself, but alas this creates a race condition.
Having two locks wouldn't assure a race-proof mutual exclusion.
This situation is best avoided by the introduction of a new, unlocked
function __test_dev_config_update_u8() which can be called from the locked
context and reducing test_dev_config_update_u8() to:
static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
{
int ret;
mutex_lock(&test_fw_mutex);
ret = __test_dev_config_update_u8(buf, size, cfg);
mutex_unlock(&test_fw_mutex);
return ret;
}
doing the locking and calling the unlocked primitive, which enables both
locked and unlocked versions without duplication of code.
The similar approach was applied to all functions called from the locked
and the unlocked context, which safely mitigates both deadlocks and race
conditions in the driver.
__test_dev_config_update_bool(), __test_dev_config_update_u8() and
__test_dev_config_update_size_t() unlocked versions of the functions
were introduced to be called from the locked contexts as a workaround
without releasing the main driver's lock and thereof causing a race
condition.
The test_dev_config_update_bool(), test_dev_config_update_u8() and
test_dev_config_update_size_t() locked versions of the functions
are being called from driver methods without the unnecessary multiplying
of the locking and unlocking code for each method, and complicating
the code with saving of the return value across lock.
Fixes: 7feebfa487b92 ("test_firmware: add support for request_firmware_into_buf")
Cc: Luis Chamberlain <mcgrof(a)kernel.org>
Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Cc: Russ Weight <russell.h.weight(a)intel.com>
Cc: Takashi Iwai <tiwai(a)suse.de>
Cc: Tianfei Zhang <tianfei.zhang(a)intel.com>
Cc: Shuah Khan <shuah(a)kernel.org>
Cc: Colin Ian King <colin.i.king(a)gmail.com>
Cc: Randy Dunlap <rdunlap(a)infradead.org>
Cc: linux-kselftest(a)vger.kernel.org
Cc: stable(a)vger.kernel.org # v5.4
Suggested-by: Dan Carpenter <error27(a)gmail.com>
Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac(a)alu.unizg.hr>
Link: https://lore.kernel.org/r/20230509084746.48259-1-mirsad.todorovac@alu.unizg…
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index 05ed84c2fc4c..35417e0af3f4 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -353,16 +353,26 @@ static ssize_t config_test_show_str(char *dst,
return len;
}
+static inline int __test_dev_config_update_bool(const char *buf, size_t size,
+ bool *cfg)
+{
+ int ret;
+
+ if (kstrtobool(buf, cfg) < 0)
+ ret = -EINVAL;
+ else
+ ret = size;
+
+ return ret;
+}
+
static int test_dev_config_update_bool(const char *buf, size_t size,
bool *cfg)
{
int ret;
mutex_lock(&test_fw_mutex);
- if (kstrtobool(buf, cfg) < 0)
- ret = -EINVAL;
- else
- ret = size;
+ ret = __test_dev_config_update_bool(buf, size, cfg);
mutex_unlock(&test_fw_mutex);
return ret;
@@ -373,7 +383,8 @@ static ssize_t test_dev_config_show_bool(char *buf, bool val)
return snprintf(buf, PAGE_SIZE, "%d\n", val);
}
-static int test_dev_config_update_size_t(const char *buf,
+static int __test_dev_config_update_size_t(
+ const char *buf,
size_t size,
size_t *cfg)
{
@@ -384,9 +395,7 @@ static int test_dev_config_update_size_t(const char *buf,
if (ret)
return ret;
- mutex_lock(&test_fw_mutex);
*(size_t *)cfg = new;
- mutex_unlock(&test_fw_mutex);
/* Always return full write size even if we didn't consume all */
return size;
@@ -402,7 +411,7 @@ static ssize_t test_dev_config_show_int(char *buf, int val)
return snprintf(buf, PAGE_SIZE, "%d\n", val);
}
-static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
+static int __test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
{
u8 val;
int ret;
@@ -411,14 +420,23 @@ static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
if (ret)
return ret;
- mutex_lock(&test_fw_mutex);
*(u8 *)cfg = val;
- mutex_unlock(&test_fw_mutex);
/* Always return full write size even if we didn't consume all */
return size;
}
+static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
+{
+ int ret;
+
+ mutex_lock(&test_fw_mutex);
+ ret = __test_dev_config_update_u8(buf, size, cfg);
+ mutex_unlock(&test_fw_mutex);
+
+ return ret;
+}
+
static ssize_t test_dev_config_show_u8(char *buf, u8 val)
{
return snprintf(buf, PAGE_SIZE, "%u\n", val);
@@ -471,10 +489,10 @@ static ssize_t config_num_requests_store(struct device *dev,
mutex_unlock(&test_fw_mutex);
goto out;
}
- mutex_unlock(&test_fw_mutex);
- rc = test_dev_config_update_u8(buf, count,
- &test_fw_config->num_requests);
+ rc = __test_dev_config_update_u8(buf, count,
+ &test_fw_config->num_requests);
+ mutex_unlock(&test_fw_mutex);
out:
return rc;
@@ -518,10 +536,10 @@ static ssize_t config_buf_size_store(struct device *dev,
mutex_unlock(&test_fw_mutex);
goto out;
}
- mutex_unlock(&test_fw_mutex);
- rc = test_dev_config_update_size_t(buf, count,
- &test_fw_config->buf_size);
+ rc = __test_dev_config_update_size_t(buf, count,
+ &test_fw_config->buf_size);
+ mutex_unlock(&test_fw_mutex);
out:
return rc;
@@ -548,10 +566,10 @@ static ssize_t config_file_offset_store(struct device *dev,
mutex_unlock(&test_fw_mutex);
goto out;
}
- mutex_unlock(&test_fw_mutex);
- rc = test_dev_config_update_size_t(buf, count,
- &test_fw_config->file_offset);
+ rc = __test_dev_config_update_size_t(buf, count,
+ &test_fw_config->file_offset);
+ mutex_unlock(&test_fw_mutex);
out:
return rc;