4.19-stable review patch. If anyone has any objections, please let me know.
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From: Stephen Boyd swboyd@chromium.org
commit baef1c90aac7e5bf13f0360a3b334825a23d31a1 upstream.
Using the batch API from the interconnect driver sometimes leads to a KASAN error due to an access to freed memory. This is easier to trigger with threadirqs on the kernel commandline.
BUG: KASAN: use-after-free in rpmh_tx_done+0x114/0x12c Read of size 1 at addr fffffff51414ad84 by task irq/110-apps_rs/57
CPU: 0 PID: 57 Comm: irq/110-apps_rs Tainted: G W 4.19.10 #72 Call trace: dump_backtrace+0x0/0x2f8 show_stack+0x20/0x2c __dump_stack+0x20/0x28 dump_stack+0xcc/0x10c print_address_description+0x74/0x240 kasan_report+0x250/0x26c __asan_report_load1_noabort+0x20/0x2c rpmh_tx_done+0x114/0x12c tcs_tx_done+0x450/0x768 irq_forced_thread_fn+0x58/0x9c irq_thread+0x120/0x1dc kthread+0x248/0x260 ret_from_fork+0x10/0x18
Allocated by task 385: kasan_kmalloc+0xac/0x148 __kmalloc+0x170/0x1e4 rpmh_write_batch+0x174/0x540 qcom_icc_set+0x8dc/0x9ac icc_set+0x288/0x2e8 a6xx_gmu_stop+0x320/0x3c0 a6xx_pm_suspend+0x108/0x124 adreno_suspend+0x50/0x60 pm_generic_runtime_suspend+0x60/0x78 __rpm_callback+0x214/0x32c rpm_callback+0x54/0x184 rpm_suspend+0x3f8/0xa90 pm_runtime_work+0xb4/0x178 process_one_work+0x544/0xbc0 worker_thread+0x514/0x7d0 kthread+0x248/0x260 ret_from_fork+0x10/0x18
Freed by task 385: __kasan_slab_free+0x12c/0x1e0 kasan_slab_free+0x10/0x1c kfree+0x134/0x588 rpmh_write_batch+0x49c/0x540 qcom_icc_set+0x8dc/0x9ac icc_set+0x288/0x2e8 a6xx_gmu_stop+0x320/0x3c0 a6xx_pm_suspend+0x108/0x124 adreno_suspend+0x50/0x60 cr50_spi spi5.0: SPI transfer timed out pm_generic_runtime_suspend+0x60/0x78 __rpm_callback+0x214/0x32c rpm_callback+0x54/0x184 rpm_suspend+0x3f8/0xa90 pm_runtime_work+0xb4/0x178 process_one_work+0x544/0xbc0 worker_thread+0x514/0x7d0 kthread+0x248/0x260 ret_from_fork+0x10/0x18
The buggy address belongs to the object at fffffff51414ac80 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 260 bytes inside of 512-byte region [fffffff51414ac80, fffffff51414ae80) The buggy address belongs to the page: page:ffffffbfd4505200 count:1 mapcount:0 mapping:fffffff51e00c680 index:0x0 compound_mapcount: 0 flags: 0x4000000000008100(slab|head) raw: 4000000000008100 ffffffbfd4529008 ffffffbfd44f9208 fffffff51e00c680 raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: fffffff51414ac80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fffffff51414ad00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
fffffff51414ad80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ fffffff51414ae00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fffffff51414ae80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
The batch API sets the same completion for each rpmh message that's sent and then loops through all the messages and waits for that single completion declared on the stack to be completed before returning from the function and freeing the message structures. Unfortunately, some messages may still be in process and 'stuck' in the TCS. At some later point, the tcs_tx_done() interrupt will run and try to process messages that have already been freed at the end of rpmh_write_batch(). This will in turn access the 'needs_free' member of the rpmh_request structure and cause KASAN to complain. Furthermore, if there's a message that's completed in rpmh_tx_done() and freed immediately after the complete() call is made we'll be racing with potentially freed memory when accessing the 'needs_free' member:
CPU0 CPU1 ---- ---- rpmh_tx_done() complete(&compl) wait_for_completion(&compl) kfree(rpm_msg) if (rpm_msg->needs_free) <KASAN warning splat>
Let's fix this by allocating a chunk of completions for each message and waiting for all of them to be completed before returning from the batch API. Alternatively, we could wait for the last message in the batch, but that may be a more complicated change because it looks like tcs_tx_done() just iterates through the indices of the queue and completes each message instead of tracking the last inserted message and completing that first.
Fixes: c8790cb6da58 ("drivers: qcom: rpmh: add support for batch RPMH request") Cc: Lina Iyer ilina@codeaurora.org Cc: "Raju P.L.S.S.S.N" rplsssn@codeaurora.org Cc: Matthias Kaehlcke mka@chromium.org Cc: Evan Green evgreen@chromium.org Cc: stable@vger.kernel.org Reviewed-by: Lina Iyer ilina@codeaurora.org Reviewed-by: Evan Green evgreen@chromium.org Signed-off-by: Stephen Boyd swboyd@chromium.org Signed-off-by: Bjorn Andersson bjorn.andersson@linaro.org Signed-off-by: Andy Gross andy.gross@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/soc/qcom/rpmh.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-)
--- a/drivers/soc/qcom/rpmh.c +++ b/drivers/soc/qcom/rpmh.c @@ -80,6 +80,7 @@ void rpmh_tx_done(const struct tcs_reque struct rpmh_request *rpm_msg = container_of(msg, struct rpmh_request, msg); struct completion *compl = rpm_msg->completion; + bool free = rpm_msg->needs_free;
rpm_msg->err = r;
@@ -94,7 +95,7 @@ void rpmh_tx_done(const struct tcs_reque complete(compl);
exit: - if (rpm_msg->needs_free) + if (free) kfree(rpm_msg); }
@@ -348,11 +349,12 @@ int rpmh_write_batch(const struct device { struct batch_cache_req *req; struct rpmh_request *rpm_msgs; - DECLARE_COMPLETION_ONSTACK(compl); + struct completion *compls; struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev); unsigned long time_left; int count = 0; - int ret, i, j; + int ret, i; + void *ptr;
if (!cmd || !n) return -EINVAL; @@ -362,10 +364,15 @@ int rpmh_write_batch(const struct device if (!count) return -EINVAL;
- req = kzalloc(sizeof(*req) + count * sizeof(req->rpm_msgs[0]), + ptr = kzalloc(sizeof(*req) + + count * (sizeof(req->rpm_msgs[0]) + sizeof(*compls)), GFP_ATOMIC); - if (!req) + if (!ptr) return -ENOMEM; + + req = ptr; + compls = ptr + sizeof(*req) + count * sizeof(*rpm_msgs); + req->count = count; rpm_msgs = req->rpm_msgs;
@@ -380,25 +387,26 @@ int rpmh_write_batch(const struct device }
for (i = 0; i < count; i++) { - rpm_msgs[i].completion = &compl; + struct completion *compl = &compls[i]; + + init_completion(compl); + rpm_msgs[i].completion = compl; ret = rpmh_rsc_send_data(ctrlr_to_drv(ctrlr), &rpm_msgs[i].msg); if (ret) { pr_err("Error(%d) sending RPMH message addr=%#x\n", ret, rpm_msgs[i].msg.cmds[0].addr); - for (j = i; j < count; j++) - rpmh_tx_done(&rpm_msgs[j].msg, ret); break; } }
time_left = RPMH_TIMEOUT_MS; - for (i = 0; i < count; i++) { - time_left = wait_for_completion_timeout(&compl, time_left); + while (i--) { + time_left = wait_for_completion_timeout(&compls[i], time_left); if (!time_left) { /* * Better hope they never finish because they'll signal - * the completion on our stack and that's bad once - * we've returned from the function. + * the completion that we're going to free once + * we've returned from this function. */ WARN_ON(1); ret = -ETIMEDOUT; @@ -407,7 +415,7 @@ int rpmh_write_batch(const struct device }
exit: - kfree(req); + kfree(ptr);
return ret; }