* [PATCH] Fix the cleanup on alloc_mpc failure in atm_mpoa_mpoad_attach
@ 2025-09-23 13:24 Deepak Sharma
2025-09-24 18:41 ` Simon Horman
2025-09-24 18:44 ` Simon Horman
0 siblings, 2 replies; 6+ messages in thread
From: Deepak Sharma @ 2025-09-23 13:24 UTC (permalink / raw)
To: davem, edumazet, kuba, pabeni, horms, pwn9uin
Cc: netdev, linux-kernel, Deepak Sharma, syzbot+07b635b9c111c566af8b
Syzbot reported a warning at `add_timer`, which is called from the
`atm_mpoa_mpoad_attach` function
The reason for this warning is that in the allocation failure by `alloc_mpc`,
there is lack of proper cleanup. And in the event that ATMMPC_CTRL ioctl is
called on to again, it will lead to the attempt of starting an already
started timer from the previous ioctl call
Do a `timer_delete` before returning from the `alloc_mpc` failure
Reported-by: syzbot+07b635b9c111c566af8b@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=07b635b9c111c566af8b
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Deepak Sharma <deepak.sharma.472935@gmail.com>
---
net/atm/mpc.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/atm/mpc.c b/net/atm/mpc.c
index f6b447bba329..cd3295c3c480 100644
--- a/net/atm/mpc.c
+++ b/net/atm/mpc.c
@@ -814,7 +814,10 @@ static int atm_mpoa_mpoad_attach(struct atm_vcc *vcc, int arg)
dprintk("allocating new mpc for itf %d\n", arg);
mpc = alloc_mpc();
if (mpc == NULL)
+ {
+ timer_delete(&mpc_timer);
return -ENOMEM;
+ }
mpc->dev_num = arg;
mpc->dev = find_lec_by_itfnum(arg);
/* NULL if there was no lec */
--
2.51.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] Fix the cleanup on alloc_mpc failure in atm_mpoa_mpoad_attach
2025-09-23 13:24 [PATCH] Fix the cleanup on alloc_mpc failure in atm_mpoa_mpoad_attach Deepak Sharma
@ 2025-09-24 18:41 ` Simon Horman
2025-09-24 18:44 ` Simon Horman
1 sibling, 0 replies; 6+ messages in thread
From: Simon Horman @ 2025-09-24 18:41 UTC (permalink / raw)
To: Deepak Sharma
Cc: davem, edumazet, kuba, pabeni, pwn9uin, netdev, linux-kernel,
syzbot+07b635b9c111c566af8b
On Tue, Sep 23, 2025 at 06:54:27PM +0530, Deepak Sharma wrote:
> Syzbot reported a warning at `add_timer`, which is called from the
> `atm_mpoa_mpoad_attach` function
>
> The reason for this warning is that in the allocation failure by `alloc_mpc`,
> there is lack of proper cleanup. And in the event that ATMMPC_CTRL ioctl is
> called on to again, it will lead to the attempt of starting an already
> started timer from the previous ioctl call
>
> Do a `timer_delete` before returning from the `alloc_mpc` failure
>
> Reported-by: syzbot+07b635b9c111c566af8b@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=07b635b9c111c566af8b
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Deepak Sharma <deepak.sharma.472935@gmail.com>
> ---
> net/atm/mpc.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/net/atm/mpc.c b/net/atm/mpc.c
> index f6b447bba329..cd3295c3c480 100644
> --- a/net/atm/mpc.c
> +++ b/net/atm/mpc.c
> @@ -814,7 +814,10 @@ static int atm_mpoa_mpoad_attach(struct atm_vcc *vcc, int arg)
> dprintk("allocating new mpc for itf %d\n", arg);
> mpc = alloc_mpc();
> if (mpc == NULL)
> + {
> + timer_delete(&mpc_timer);
> return -ENOMEM;
> + }
> mpc->dev_num = arg;
> mpc->dev = find_lec_by_itfnum(arg);
> /* NULL if there was no lec */
Hi Deepak.
I have a few questions about this.
1. Is timer_delete() sufficient, or is timer_delete_sync() needed
to avoid the timer being rearmed?
2. If timer_delete_sync() is needed here, then it is probably
also needed a few lines above, in place of an existing call to
timer_delete().
3. Is timer_delete()/timer_delete_sync() also needed for the error condition a
few lines below the hunk above? That code looks like this:
if (mpc->mpoad_vcc) {
pr_info("mpoad is already present for itf %d\n", arg);
return -EADDRINUSE;
}
Also, this patch is probably for net. So, for reference, it should
be targeted at that tree like this:
Subject: [PATCH net] ...
And the patch subject should have a prefix. Looking at git history, "atm:"
seems appropriate.
Subject: [PATCH net] atm: ...
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] Fix the cleanup on alloc_mpc failure in atm_mpoa_mpoad_attach
2025-09-23 13:24 [PATCH] Fix the cleanup on alloc_mpc failure in atm_mpoa_mpoad_attach Deepak Sharma
2025-09-24 18:41 ` Simon Horman
@ 2025-09-24 18:44 ` Simon Horman
2025-09-24 23:45 ` Jakub Kicinski
1 sibling, 1 reply; 6+ messages in thread
From: Simon Horman @ 2025-09-24 18:44 UTC (permalink / raw)
To: Deepak Sharma
Cc: davem, edumazet, kuba, pabeni, pwn9uin, netdev, linux-kernel,
syzbot+07b635b9c111c566af8b
On Tue, Sep 23, 2025 at 06:54:27PM +0530, Deepak Sharma wrote:
> Syzbot reported a warning at `add_timer`, which is called from the
> `atm_mpoa_mpoad_attach` function
>
> The reason for this warning is that in the allocation failure by `alloc_mpc`,
> there is lack of proper cleanup. And in the event that ATMMPC_CTRL ioctl is
> called on to again, it will lead to the attempt of starting an already
> started timer from the previous ioctl call
>
> Do a `timer_delete` before returning from the `alloc_mpc` failure
>
> Reported-by: syzbot+07b635b9c111c566af8b@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=07b635b9c111c566af8b
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Deepak Sharma <deepak.sharma.472935@gmail.com>
> ---
> net/atm/mpc.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/net/atm/mpc.c b/net/atm/mpc.c
> index f6b447bba329..cd3295c3c480 100644
> --- a/net/atm/mpc.c
> +++ b/net/atm/mpc.c
> @@ -814,7 +814,10 @@ static int atm_mpoa_mpoad_attach(struct atm_vcc *vcc, int arg)
> dprintk("allocating new mpc for itf %d\n", arg);
> mpc = alloc_mpc();
> if (mpc == NULL)
> + {
Sorry for not mentioning this in my previous email.
The preferred coding style is:
if (mpc == NULL) {
> + timer_delete(&mpc_timer);
> return -ENOMEM;
> + }
> mpc->dev_num = arg;
> mpc->dev = find_lec_by_itfnum(arg);
> /* NULL if there was no lec */
--
pw-bot: changes-requested
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] Fix the cleanup on alloc_mpc failure in atm_mpoa_mpoad_attach
@ 2025-09-25 20:40 Deepak Sharma
2025-09-28 15:26 ` David Hunter
0 siblings, 1 reply; 6+ messages in thread
From: Deepak Sharma @ 2025-09-25 20:40 UTC (permalink / raw)
To: davem, edumazet, kuba, pabeni, horms, pwn9uin
Cc: netdev, linux-kernel, linux-kernel-mentees, david.hunter.linux,
skhan, syzbot+740e04c2a93467a0f8c8, Deepak Sharma,
syzbot+07b635b9c111c566af8b
Syzbot reported a warning at `add_timer`, which is called from the
`atm_mpoa_mpoad_attach` function
The reason for this warning is that in the allocation failure by `alloc_mpc`,
there is lack of proper cleanup. And in the event that ATMMPC_CTRL ioctl is
called on to again, it will lead to the attempt of starting an already
started timer from the previous ioctl call
Do a `timer_delete` before returning from the `alloc_mpc` failure
Reported-by: syzbot+07b635b9c111c566af8b@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=07b635b9c111c566af8b
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Deepak Sharma <deepak.sharma.472935@gmail.com>
---
net/atm/mpc.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/atm/mpc.c b/net/atm/mpc.c
index f6b447bba329..cd3295c3c480 100644
--- a/net/atm/mpc.c
+++ b/net/atm/mpc.c
@@ -814,7 +814,10 @@ static int atm_mpoa_mpoad_attach(struct atm_vcc *vcc, int arg)
dprintk("allocating new mpc for itf %d\n", arg);
mpc = alloc_mpc();
if (mpc == NULL)
+ {
+ timer_delete(&mpc_timer);
return -ENOMEM;
+ }
mpc->dev_num = arg;
mpc->dev = find_lec_by_itfnum(arg);
/* NULL if there was no lec */
--
2.51.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] Fix the cleanup on alloc_mpc failure in atm_mpoa_mpoad_attach
2025-09-25 20:40 Deepak Sharma
@ 2025-09-28 15:26 ` David Hunter
0 siblings, 0 replies; 6+ messages in thread
From: David Hunter @ 2025-09-28 15:26 UTC (permalink / raw)
To: Deepak Sharma, davem, edumazet, kuba, pabeni, horms, pwn9uin
Cc: netdev, linux-kernel, linux-kernel-mentees, skhan,
syzbot+740e04c2a93467a0f8c8, syzbot+07b635b9c111c566af8b
On 9/25/25 16:40, Deepak Sharma wrote:
>
> Do a `timer_delete` before returning from the `alloc_mpc` failure
>
Was this code tested?
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2025-09-28 15:26 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-09-23 13:24 [PATCH] Fix the cleanup on alloc_mpc failure in atm_mpoa_mpoad_attach Deepak Sharma
2025-09-24 18:41 ` Simon Horman
2025-09-24 18:44 ` Simon Horman
2025-09-24 23:45 ` Jakub Kicinski
-- strict thread matches above, loose matches on Subject: below --
2025-09-25 20:40 Deepak Sharma
2025-09-28 15:26 ` David Hunter
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).