[ixgbe] Crash when running an XDP program

[ixgbe] Crash when running an XDP program

[Toke Høiland-Jørgensen]

Hi folks,

Our LNST testing team uncovered a crash in ixgbe when running an XDP
program, see this report:
https://bugzilla.redhat.com/show_bug.cgi?id=2343204

From looking at the code, it seems to me that the culprit is this commit:

c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in ixgbe_run_xdp()")

after that commit, the IS_ERR(skb) check in ixgbe_put_rx_buffer() no
longer triggers, and that function tries to dereference a NULL skb
pointer after an XDP program dropped the frame.

Could you please fix this?

And, erm, given the number of reviewed-by and tested-by tags in the
commit above, I'm guessing you don't have any XDP tests in your testing
regimen? Any chance you could add that? :)

Thanks!

-Toke

Re: [ixgbe] Crash when running an XDP program

[Maciej Fijalkowski]

On Wed, Feb 12, 2025 at 01:33:09PM +0100, Toke Høiland-Jørgensen wrote:
> Hi folks,
> 
> Our LNST testing team uncovered a crash in ixgbe when running an XDP
> program, see this report:
> https://bugzilla.redhat.com/show_bug.cgi?id=2343204
> 
> From looking at the code, it seems to me that the culprit is this commit:
> 
> c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in ixgbe_run_xdp()")
> 
> after that commit, the IS_ERR(skb) check in ixgbe_put_rx_buffer() no
> longer triggers, and that function tries to dereference a NULL skb
> pointer after an XDP program dropped the frame.
> 
> Could you please fix this?

Hi Toke,

https://lore.kernel.org/netdev/20250211214343.4092496-5-anthony.l.nguyen@intel.com/

can you see if this fixes it?

Validation in our company has always been a mystery to me, sorry for this
inconvenience and that we were bad at reviewing :<

> 
> And, erm, given the number of reviewed-by and tested-by tags in the
> commit above, I'm guessing you don't have any XDP tests in your testing
> regimen? Any chance you could add that? :)
> 
> Thanks!
> 
> -Toke
> 

Re: [ixgbe] Crash when running an XDP program

[Toke Høiland-Jørgensen]

Maciej Fijalkowski <maciej.fijalkowski@intel.com> writes:

> On Wed, Feb 12, 2025 at 01:33:09PM +0100, Toke Høiland-Jørgensen wrote:
>> Hi folks,
>> 
>> Our LNST testing team uncovered a crash in ixgbe when running an XDP
>> program, see this report:
>> https://bugzilla.redhat.com/show_bug.cgi?id=2343204
>> 
>> From looking at the code, it seems to me that the culprit is this commit:
>> 
>> c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in ixgbe_run_xdp()")
>> 
>> after that commit, the IS_ERR(skb) check in ixgbe_put_rx_buffer() no
>> longer triggers, and that function tries to dereference a NULL skb
>> pointer after an XDP program dropped the frame.
>> 
>> Could you please fix this?
>
> Hi Toke,
>
> https://lore.kernel.org/netdev/20250211214343.4092496-5-anthony.l.nguyen@intel.com/
>
> can you see if this fixes it?

Ah! I went looking in the -net and -net-next git trees to see if you'd
already fixed this, but didn't check the list. Thanks for the pointer,
will see if we can get this tested.

> Validation in our company has always been a mystery to me, sorry for this
> inconvenience and that we were bad at reviewing :<

No worries, bugs happen; thankfully we caught it early. Also mostly
meant it as a nudge to try to give XDP testing a more prominent spot :)

-Toke

Re: [ixgbe] Crash when running an XDP program

[Samuel Dobron]

Hey,

Thanks for cooperation. The issue seems to be fixed in
kernel-6.14.0-0.rc3.29.eln146.

Sam.

On Wed, Feb 12, 2025 at 2:04 PM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Maciej Fijalkowski <maciej.fijalkowski@intel.com> writes:
>
> > On Wed, Feb 12, 2025 at 01:33:09PM +0100, Toke Høiland-Jørgensen wrote:
> >> Hi folks,
> >>
> >> Our LNST testing team uncovered a crash in ixgbe when running an XDP
> >> program, see this report:
> >> https://bugzilla.redhat.com/show_bug.cgi?id=2343204
> >>
> >> From looking at the code, it seems to me that the culprit is this commit:
> >>
> >> c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in ixgbe_run_xdp()")
> >>
> >> after that commit, the IS_ERR(skb) check in ixgbe_put_rx_buffer() no
> >> longer triggers, and that function tries to dereference a NULL skb
> >> pointer after an XDP program dropped the frame.
> >>
> >> Could you please fix this?
> >
> > Hi Toke,
> >
> > https://lore.kernel.org/netdev/20250211214343.4092496-5-anthony.l.nguyen@intel.com/
> >
> > can you see if this fixes it?
>
> Ah! I went looking in the -net and -net-next git trees to see if you'd
> already fixed this, but didn't check the list. Thanks for the pointer,
> will see if we can get this tested.
>
> > Validation in our company has always been a mystery to me, sorry for this
> > inconvenience and that we were bad at reviewing :<
>
> No worries, bugs happen; thankfully we caught it early. Also mostly
> meant it as a nudge to try to give XDP testing a more prominent spot :)
>
> -Toke
>