The current implementation of PTRACE_KILL is buggy and has been for
many years as it assumes it's target has stopped in ptrace_stop. At a
quick skim it looks like this assumption has existed since ptrace
support was added in linux v1.0.
While PTRACE_KILL has been deprecated we can not remove it as
a quick search with google code search reveals many existing
programs calling it.
When the ptracee is not stopped at ptrace_stop some fields would be
set that are ignored except in ptrace_stop. Making the userspace
visible behavior of PTRACE_KILL a noop in those case.
As the usual rules are not obeyed it is not clear what the
consequences are of calling PTRACE_KILL on a running process.
Presumably userspace does not do this as it achieves nothing.
Replace the implementation of PTRACE_KILL with a simple
send_sig_info(SIGKILL) followed by a return 0. This changes the
observable user space behavior only in that PTRACE_KILL on a process
not stopped in ptrace_stop will also kill it. As that has always
been the intent of the code this seems like a reasonable change.
Cc: stable(a)vger.kernel.org
Reported-by: Al Viro <viro(a)zeniv.linux.org.uk>
Suggested-by: Al Viro <viro(a)zeniv.linux.org.uk>
Signed-off-by: "Eric W. Biederman" <ebiederm(a)xmission.com>
---
arch/x86/kernel/step.c | 3 +--
kernel/ptrace.c | 5 ++---
2 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index 0f3c307b37b3..8e2b2552b5ee 100644
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -180,8 +180,7 @@ void set_task_blockstep(struct task_struct *task, bool on)
*
* NOTE: this means that set/clear TIF_BLOCKSTEP is only safe if
* task is current or it can't be running, otherwise we can race
- * with __switch_to_xtra(). We rely on ptrace_freeze_traced() but
- * PTRACE_KILL is not safe.
+ * with __switch_to_xtra(). We rely on ptrace_freeze_traced().
*/
local_irq_disable();
debugctl = get_debugctlmsr();
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index da30dcd477a0..7105821595bc 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -1236,9 +1236,8 @@ int ptrace_request(struct task_struct *child, long request,
return ptrace_resume(child, request, data);
case PTRACE_KILL:
- if (child->exit_state) /* already dead */
- return 0;
- return ptrace_resume(child, request, SIGKILL);
+ send_sig_info(SIGKILL, SEND_SIG_NOINFO, child);
+ return 0;
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
case PTRACE_GETREGSET:
--
2.35.3
xtensa is the last user of the PT_SINGLESTEP flag. Changing tsk->ptrace in
user_enable_single_step and user_disable_single_step without locking could
potentiallly cause problems.
So use a thread info flag instead of a flag in tsk->ptrace. Use TIF_SINGLESTEP
that xtensa already had defined but unused.
Remove the definitions of PT_SINGLESTEP and PT_BLOCKSTEP as they have no more users.
Cc: stable(a)vger.kernel.org
Acked-by: Max Filippov <jcmvbkbc(a)gmail.com>
Signed-off-by: "Eric W. Biederman" <ebiederm(a)xmission.com>
---
arch/xtensa/kernel/ptrace.c | 4 ++--
arch/xtensa/kernel/signal.c | 4 ++--
include/linux/ptrace.h | 6 ------
3 files changed, 4 insertions(+), 10 deletions(-)
diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c
index 323c678a691f..b952e67cc0cc 100644
--- a/arch/xtensa/kernel/ptrace.c
+++ b/arch/xtensa/kernel/ptrace.c
@@ -225,12 +225,12 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task)
void user_enable_single_step(struct task_struct *child)
{
- child->ptrace |= PT_SINGLESTEP;
+ set_tsk_thread_flag(child, TIF_SINGLESTEP);
}
void user_disable_single_step(struct task_struct *child)
{
- child->ptrace &= ~PT_SINGLESTEP;
+ clear_tsk_thread_flag(child, TIF_SINGLESTEP);
}
/*
diff --git a/arch/xtensa/kernel/signal.c b/arch/xtensa/kernel/signal.c
index 6f68649e86ba..ac50ec46c8f1 100644
--- a/arch/xtensa/kernel/signal.c
+++ b/arch/xtensa/kernel/signal.c
@@ -473,7 +473,7 @@ static void do_signal(struct pt_regs *regs)
/* Set up the stack frame */
ret = setup_frame(&ksig, sigmask_to_save(), regs);
signal_setup_done(ret, &ksig, 0);
- if (current->ptrace & PT_SINGLESTEP)
+ if (test_thread_flag(TIF_SINGLESTEP))
task_pt_regs(current)->icountlevel = 1;
return;
@@ -499,7 +499,7 @@ static void do_signal(struct pt_regs *regs)
/* If there's no signal to deliver, we just restore the saved mask. */
restore_saved_sigmask();
- if (current->ptrace & PT_SINGLESTEP)
+ if (test_thread_flag(TIF_SINGLESTEP))
task_pt_regs(current)->icountlevel = 1;
return;
}
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index 4c06f9f8ef3f..c952c5ba8fab 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -46,12 +46,6 @@ extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
#define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
#define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
-/* single stepping state bits (used on ARM and PA-RISC) */
-#define PT_SINGLESTEP_BIT 31
-#define PT_SINGLESTEP (1<<PT_SINGLESTEP_BIT)
-#define PT_BLOCKSTEP_BIT 30
-#define PT_BLOCKSTEP (1<<PT_BLOCKSTEP_BIT)
-
extern long arch_ptrace(struct task_struct *child, long request,
unsigned long addr, unsigned long data);
extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
--
2.35.3
The patch below does not apply to the 4.19-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>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From e914d8f00391520ecc4495dd0ca0124538ab7119 Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan(a)kernel.org>
Date: Thu, 14 Apr 2022 19:13:46 -0700
Subject: [PATCH] mm: fix unexpected zeroed page mapping with zram swap
Two processes under CLONE_VM cloning, user process can be corrupted by
seeing zeroed page unexpectedly.
CPU A CPU B
do_swap_page do_swap_page
SWP_SYNCHRONOUS_IO path SWP_SYNCHRONOUS_IO path
swap_readpage valid data
swap_slot_free_notify
delete zram entry
swap_readpage zeroed(invalid) data
pte_lock
map the *zero data* to userspace
pte_unlock
pte_lock
if (!pte_same)
goto out_nomap;
pte_unlock
return and next refault will
read zeroed data
The swap_slot_free_notify is bogus for CLONE_VM case since it doesn't
increase the refcount of swap slot at copy_mm so it couldn't catch up
whether it's safe or not to discard data from backing device. In the
case, only the lock it could rely on to synchronize swap slot freeing is
page table lock. Thus, this patch gets rid of the swap_slot_free_notify
function. With this patch, CPU A will see correct data.
CPU A CPU B
do_swap_page do_swap_page
SWP_SYNCHRONOUS_IO path SWP_SYNCHRONOUS_IO path
swap_readpage original data
pte_lock
map the original data
swap_free
swap_range_free
bd_disk->fops->swap_slot_free_notify
swap_readpage read zeroed data
pte_unlock
pte_lock
if (!pte_same)
goto out_nomap;
pte_unlock
return
on next refault will see mapped data by CPU B
The concern of the patch would increase memory consumption since it
could keep wasted memory with compressed form in zram as well as
uncompressed form in address space. However, most of cases of zram uses
no readahead and do_swap_page is followed by swap_free so it will free
the compressed form from in zram quickly.
Link: https://lkml.kernel.org/r/YjTVVxIAsnKAXjTd@google.com
Fixes: 0bcac06f27d7 ("mm, swap: skip swapcache for swapin of synchronous device")
Reported-by: Ivan Babrou <ivan(a)cloudflare.com>
Tested-by: Ivan Babrou <ivan(a)cloudflare.com>
Signed-off-by: Minchan Kim <minchan(a)kernel.org>
Cc: Nitin Gupta <ngupta(a)vflare.org>
Cc: Sergey Senozhatsky <senozhatsky(a)chromium.org>
Cc: Jens Axboe <axboe(a)kernel.dk>
Cc: David Hildenbrand <david(a)redhat.com>
Cc: <stable(a)vger.kernel.org> [4.14+]
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org>
diff --git a/mm/page_io.c b/mm/page_io.c
index b417f000b49e..89fbf3cae30f 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -51,54 +51,6 @@ void end_swap_bio_write(struct bio *bio)
bio_put(bio);
}
-static void swap_slot_free_notify(struct page *page)
-{
- struct swap_info_struct *sis;
- struct gendisk *disk;
- swp_entry_t entry;
-
- /*
- * There is no guarantee that the page is in swap cache - the software
- * suspend code (at least) uses end_swap_bio_read() against a non-
- * swapcache page. So we must check PG_swapcache before proceeding with
- * this optimization.
- */
- if (unlikely(!PageSwapCache(page)))
- return;
-
- sis = page_swap_info(page);
- if (data_race(!(sis->flags & SWP_BLKDEV)))
- return;
-
- /*
- * The swap subsystem performs lazy swap slot freeing,
- * expecting that the page will be swapped out again.
- * So we can avoid an unnecessary write if the page
- * isn't redirtied.
- * This is good for real swap storage because we can
- * reduce unnecessary I/O and enhance wear-leveling
- * if an SSD is used as the as swap device.
- * But if in-memory swap device (eg zram) is used,
- * this causes a duplicated copy between uncompressed
- * data in VM-owned memory and compressed data in
- * zram-owned memory. So let's free zram-owned memory
- * and make the VM-owned decompressed page *dirty*,
- * so the page should be swapped out somewhere again if
- * we again wish to reclaim it.
- */
- disk = sis->bdev->bd_disk;
- entry.val = page_private(page);
- if (disk->fops->swap_slot_free_notify && __swap_count(entry) == 1) {
- unsigned long offset;
-
- offset = swp_offset(entry);
-
- SetPageDirty(page);
- disk->fops->swap_slot_free_notify(sis->bdev,
- offset);
- }
-}
-
static void end_swap_bio_read(struct bio *bio)
{
struct page *page = bio_first_page_all(bio);
@@ -114,7 +66,6 @@ static void end_swap_bio_read(struct bio *bio)
}
SetPageUptodate(page);
- swap_slot_free_notify(page);
out:
unlock_page(page);
WRITE_ONCE(bio->bi_private, NULL);
@@ -394,11 +345,6 @@ int swap_readpage(struct page *page, bool synchronous)
if (sis->flags & SWP_SYNCHRONOUS_IO) {
ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
if (!ret) {
- if (trylock_page(page)) {
- swap_slot_free_notify(page);
- unlock_page(page);
- }
-
count_vm_event(PSWPIN);
goto out;
}
> I also probably can't test hibernation, never managed to get it
> working before. I'll give it a shot tomorrow though if I have time but
> I don't even have swap set up ATM.
That’s a pity, but okay, of course. Thanks for reporting this bug.
Since you are using Arch and the Wiki is quite detailed, you could try
setting up a swap on an unused USB stick floating around. This should be
the easiest setup. Make sure to add resume to the mkinitcpio hooks after
udev, but before fsck and add the resume parameter to your bootloader as
described in the Wiki. This should get you going.
Don’t make this a permanent setup, if you use encryption or like
performance. The permanent solution would be creating a swap partition
or, if that is not feasible, a swap file while considering the Wiki
notes for e.g. btrfs.
Best regards,
Manuel
The following commit has been merged into the irq/urgent branch of tip:
Commit-ID: 8707898e22fd665bc1d7b18b809be4b56ce25bdd
Gitweb: https://git.kernel.org/tip/8707898e22fd665bc1d7b18b809be4b56ce25bdd
Author: Thomas Pfaff <tpfaff(a)pcs.com>
AuthorDate: Mon, 02 May 2022 13:28:29 +02:00
Committer: Thomas Gleixner <tglx(a)linutronix.de>
CommitterDate: Thu, 05 May 2022 11:54:05 +02:00
genirq: Synchronize interrupt thread startup
A kernel hang can be observed when running setserial in a loop on a kernel
with force threaded interrupts. The sequence of events is:
setserial
open("/dev/ttyXXX")
request_irq()
do_stuff()
-> serial interrupt
-> wake(irq_thread)
desc->threads_active++;
close()
free_irq()
kthread_stop(irq_thread)
synchronize_irq() <- hangs because desc->threads_active != 0
The thread is created in request_irq() and woken up, but does not get on a
CPU to reach the actual thread function, which would handle the pending
wake-up. kthread_stop() sets the should stop condition which makes the
thread immediately exit, which in turn leaves the stale threads_active
count around.
This problem was introduced with commit 519cc8652b3a, which addressed a
interrupt sharing issue in the PCIe code.
Before that commit free_irq() invoked synchronize_irq(), which waits for
the hard interrupt handler and also for associated threads to complete.
To address the PCIe issue synchronize_irq() was replaced with
__synchronize_hardirq(), which only waits for the hard interrupt handler to
complete, but not for threaded handlers.
This was done under the assumption, that the interrupt thread already
reached the thread function and waits for a wake-up, which is guaranteed to
be handled before acting on the stop condition. The problematic case, that
the thread would not reach the thread function, was obviously overlooked.
Make sure that the interrupt thread is really started and reaches
thread_fn() before returning from __setup_irq().
This utilizes the existing wait queue in the interrupt descriptor. The
wait queue is unused for non-shared interrupts. For shared interrupts the
usage might cause a spurious wake-up of a waiter in synchronize_irq() or the
completion of a threaded handler might cause a spurious wake-up of the
waiter for the ready flag. Both are harmless and have no functional impact.
[ tglx: Amended changelog ]
Fixes: 519cc8652b3a ("genirq: Synchronize only with single thread on free_irq()")
Signed-off-by: Thomas Pfaff <tpfaff(a)pcs.com>
Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de>
Reviewed-by: Marc Zyngier <maz(a)kernel.org>
Cc: stable(a)vger.kernel.org
Link: https://lore.kernel.org/r/552fe7b4-9224-b183-bb87-a8f36d335690@pcs.com
---
kernel/irq/internals.h | 2 ++
kernel/irq/irqdesc.c | 2 ++
kernel/irq/manage.c | 39 +++++++++++++++++++++++++++++----------
3 files changed, 33 insertions(+), 10 deletions(-)
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 99cbdf5..f09c603 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -29,12 +29,14 @@ extern struct irqaction chained_action;
* IRQTF_WARNED - warning "IRQ_WAKE_THREAD w/o thread_fn" has been printed
* IRQTF_AFFINITY - irq thread is requested to adjust affinity
* IRQTF_FORCED_THREAD - irq action is force threaded
+ * IRQTF_READY - signals that irq thread is ready
*/
enum {
IRQTF_RUNTHREAD,
IRQTF_WARNED,
IRQTF_AFFINITY,
IRQTF_FORCED_THREAD,
+ IRQTF_READY,
};
/*
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 939d21c..0099b87 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -407,6 +407,7 @@ static struct irq_desc *alloc_desc(int irq, int node, unsigned int flags,
lockdep_set_class(&desc->lock, &irq_desc_lock_class);
mutex_init(&desc->request_mutex);
init_rcu_head(&desc->rcu);
+ init_waitqueue_head(&desc->wait_for_threads);
desc_set_defaults(irq, desc, node, affinity, owner);
irqd_set(&desc->irq_data, flags);
@@ -575,6 +576,7 @@ int __init early_irq_init(void)
raw_spin_lock_init(&desc[i].lock);
lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);
mutex_init(&desc[i].request_mutex);
+ init_waitqueue_head(&desc[i].wait_for_threads);
desc_set_defaults(i, &desc[i], node, NULL, NULL);
}
return arch_early_irq_init();
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index c03f71d..e3e245a 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1249,6 +1249,31 @@ static void irq_wake_secondary(struct irq_desc *desc, struct irqaction *action)
}
/*
+ * Internal function to notify that a interrupt thread is ready.
+ */
+static void irq_thread_set_ready(struct irq_desc *desc,
+ struct irqaction *action)
+{
+ set_bit(IRQTF_READY, &action->thread_flags);
+ wake_up(&desc->wait_for_threads);
+}
+
+/*
+ * Internal function to wake up a interrupt thread and wait until it is
+ * ready.
+ */
+static void wake_up_and_wait_for_irq_thread_ready(struct irq_desc *desc,
+ struct irqaction *action)
+{
+ if (!action || !action->thread)
+ return;
+
+ wake_up_process(action->thread);
+ wait_event(desc->wait_for_threads,
+ test_bit(IRQTF_READY, &action->thread_flags));
+}
+
+/*
* Interrupt handler thread
*/
static int irq_thread(void *data)
@@ -1259,6 +1284,8 @@ static int irq_thread(void *data)
irqreturn_t (*handler_fn)(struct irq_desc *desc,
struct irqaction *action);
+ irq_thread_set_ready(desc, action);
+
sched_set_fifo(current);
if (force_irqthreads() && test_bit(IRQTF_FORCED_THREAD,
@@ -1683,8 +1710,6 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
}
if (!shared) {
- init_waitqueue_head(&desc->wait_for_threads);
-
/* Setup the type (level, edge polarity) if configured: */
if (new->flags & IRQF_TRIGGER_MASK) {
ret = __irq_set_trigger(desc,
@@ -1780,14 +1805,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
irq_setup_timings(desc, new);
- /*
- * Strictly no need to wake it up, but hung_task complains
- * when no hard interrupt wakes the thread up.
- */
- if (new->thread)
- wake_up_process(new->thread);
- if (new->secondary)
- wake_up_process(new->secondary->thread);
+ wake_up_and_wait_for_irq_thread_ready(desc, new);
+ wake_up_and_wait_for_irq_thread_ready(desc, new->secondary);
register_irq_proc(irq, desc);
new->dir = NULL;
Hi,
A changed was added to both version 5.17.5 and 5.15.36 which causes my computer to freeze when resuming after a suspend. This happens every time I suspend and then resume.
I've bisected the change to commit: cbe6c3a8f8f4315b96e46e1a1c70393c06d95a4c (net: atlantic: invert deep par in pm functions, preventing null derefs)
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=…
My computer details that might be relevant:
OS: Arch Linux
CPU: AMD 5950X
GPU: AMD 6800XT
As expected I have an Aquantia ethernet controller listed in lspci:
05:00.0 Ethernet controller: Aquantia Corp. AQC107 NBase-T/IEEE 802.3bz Ethernet Controller [AQtion] (rev 02)
Please let me know if there is any more info I can give that will help.
Regards,
Jordan
From: Jason Ekstrand <jason(a)jlekstrand.net>
This reverts commit 9e31c1fe45d555a948ff66f1f0e3fe1f83ca63f7. Ever
since that commit, we've been having issues where a hang in one client
can propagate to another. In particular, a hang in an app can propagate
to the X server which causes the whole desktop to lock up.
Error propagation along fences sound like a good idea, but as your bug
shows, surprising consequences, since propagating errors across security
boundaries is not a good thing.
What we do have is track the hangs on the ctx, and report information to
userspace using RESET_STATS. That's how arb_robustness works. Also, if my
understanding is still correct, the EIO from execbuf is when your context
is banned (because not recoverable or too many hangs). And in all these
cases it's up to userspace to figure out what is all impacted and should
be reported to the application, that's not on the kernel to guess and
automatically propagate.
What's more, we're also building more features on top of ctx error
reporting with RESET_STATS ioctl: Encrypted buffers use the same, and the
userspace fence wait also relies on that mechanism. So it is the path
going forward for reporting gpu hangs and resets to userspace.
So all together that's why I think we should just bury this idea again as
not quite the direction we want to go to, hence why I think the revert is
the right option here.
For backporters: Please note that you _must_ have a backport of
https://lore.kernel.org/dri-devel/20210602164149.391653-2-jason@jlekstrand.…
for otherwise backporting just this patch opens up a security bug.
v2: Augment commit message. Also restore Jason's sob that I
accidentally lost.
v3: Add a note for backporters
Signed-off-by: Jason Ekstrand <jason(a)jlekstrand.net>
Reported-by: Marcin Slusarz <marcin.slusarz(a)intel.com>
Cc: <stable(a)vger.kernel.org> # v5.6+
Cc: Jason Ekstrand <jason.ekstrand(a)intel.com>
Cc: Marcin Slusarz <marcin.slusarz(a)intel.com>
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/3080
Fixes: 9e31c1fe45d5 ("drm/i915: Propagate errors on awaiting already signaled fences")
Acked-by: Daniel Vetter <daniel.vetter(a)ffwll.ch>
Reviewed-by: Jon Bloomfield <jon.bloomfield(a)intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter(a)ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210714193419.1459723-3-jaso…
(cherry picked from commit 93a2711cddd5760e2f0f901817d71c93183c3b87)
---
drivers/gpu/drm/i915/i915_request.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 8e310b8dd91c..6a5070399c04 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1297,10 +1297,8 @@ i915_request_await_execution(struct i915_request *rq,
do {
fence = *child++;
- if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
- i915_sw_fence_set_error_once(&rq->submit, fence->error);
+ if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
continue;
- }
if (fence->context == rq->fence.context)
continue;
@@ -1398,10 +1396,8 @@ i915_request_await_dma_fence(struct i915_request *rq, struct dma_fence *fence)
do {
fence = *child++;
- if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
- i915_sw_fence_set_error_once(&rq->submit, fence->error);
+ if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
continue;
- }
/*
* Requests on the same timeline are explicitly ordered, along