[PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail

[PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail

[Jinchao Wang]

sched_mm_cid_after_execve() is called from the failure path
of bprm_execve(). At that point exec has not completed successfully,
so updating the mm CID state is incorrect and can trigger a panic,
as reported by syzbot.

Remove the call from the exec failure path.

Cc: stable@vger.kernel.org
Reported-by: syzbot+9ca2c6e6b098bf5ae60a@syzkaller.appspotmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
---
 fs/exec.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/exec.c b/fs/exec.c
index 9d5ebc9d15b0..9044a75d26ab 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1773,7 +1773,6 @@ static int bprm_execve(struct linux_binprm *bprm)
 	if (bprm->point_of_no_return && !fatal_signal_pending(current))
 		force_fatal_sig(SIGSEGV);
 
-	sched_mm_cid_after_execve(current);
 	rseq_force_update();
 	current->in_execve = 0;
 
-- 
2.43.0

Re: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail

[Jinchao Wang]

On Thu, Dec 18, 2025 at 11:23:23AM +0800, Jinchao Wang wrote:

Hi, mathieu

Please review this patch for mm_cid.

The syzbot test failure occurs because the syz-repro breaks the system
state, causing all user commands to fail. Actually the syz-rero can only
trigger a panic or error.

The broken system can be recovered by resetting binfmt_misc with:

echo 0 > /proc/sys/fs/binfmt_misc/status


Thanks.

Cc: mathieu.desnoyers@efficios.com
> sched_mm_cid_after_execve() is called from the failure path
> of bprm_execve(). At that point exec has not completed successfully,
> so updating the mm CID state is incorrect and can trigger a panic,
> as reported by syzbot.
> 
> Remove the call from the exec failure path.
> 
> Cc: stable@vger.kernel.org
> Reported-by: syzbot+9ca2c6e6b098bf5ae60a@syzkaller.appspotmail.com
> Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
> ---
>  fs/exec.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/fs/exec.c b/fs/exec.c
> index 9d5ebc9d15b0..9044a75d26ab 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -1773,7 +1773,6 @@ static int bprm_execve(struct linux_binprm *bprm)
>  	if (bprm->point_of_no_return && !fatal_signal_pending(current))
>  		force_fatal_sig(SIGSEGV);
>  
> -	sched_mm_cid_after_execve(current);
>  	rseq_force_update();
>  	current->in_execve = 0;
>  
> -- 
> 2.43.0
> 

Re: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail

[Mathieu Desnoyers]

On 2025-12-24 07:10, Jinchao Wang wrote:
> On Thu, Dec 18, 2025 at 11:23:23AM +0800, Jinchao Wang wrote:
> 
> Hi, mathieu
> 
> Please review this patch for mm_cid.

Nack. Your fix lacks context and removes a needed call in the
common case to fix what I understand to be a init task issue.

See this patch instead which addresses an issue very similar to
yours removing the relevant sched_mm_cid_after_exec() call:

https://lore.kernel.org/lkml/20251223215113.639686-1-xiyou.wangcong@gmail.com/

I added Thomas Gleixner in CC.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com

Re: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail

[Jinchao Wang]

On Wed, Dec 24, 2025 at 08:52:16AM -0500, Mathieu Desnoyers wrote:
> On 2025-12-24 07:10, Jinchao Wang wrote:
> > On Thu, Dec 18, 2025 at 11:23:23AM +0800, Jinchao Wang wrote:
> > 
> > Hi, mathieu
> > 
> > Please review this patch for mm_cid.
> 
> Nack. Your fix lacks context and removes a needed call in the
> common case to fix what I understand to be a init task issue.
> 
> See this patch instead which addresses an issue very similar to
> yours removing the relevant sched_mm_cid_after_exec() call:
> 
> https://lore.kernel.org/lkml/20251223215113.639686-1-xiyou.wangcong@gmail.com/

Yes, they are same issue and this patch works.
Thanks.

> 
> I added Thomas Gleixner in CC.
> 
> Thanks,
> 
> Mathieu
> 
> -- 
> Mathieu Desnoyers
> EfficiOS Inc.
> https://www.efficios.com