Re: [PATCH net 1/1] tcp: check skb is non-NULL in tcp_rto_delta_us()

[Josh Hunt]

On 8/22/24 11:55 PM, Eric Dumazet wrote:
> On Fri, Aug 23, 2024 at 5:34 AM Josh Hunt <johunt@xxxxxxxxxx> wrote:
> > There have been multiple occassions where we have crashed in this path
> > because packets_out suggested there were packets on the write or retransmit
> > queues, but in fact there weren't leading to a NULL skb being dereferenced.
> > While we should fix that root cause we should also just make sure the skb
> > is not NULL before dereferencing it. Also add a warn once here to capture
> > some information if/when the problem case is hit again.
> >
> > Signed-off-by: Josh Hunt <johunt@xxxxxxxxxx>
>
> Hi Josh
>
> We do not want a patch series of one patch, with the stack trace in
> the cover letter.
> Please send a standalone patch, with all the information in its changelog.
>
> 1) Add Neal Cardwell in the CC list.

Sending v2 now with Neal included.

> 2) Are you using TCP_REPAIR by any chance ?

No, we're not using TCP_REPAIR on these machines.

> 3) Please double check your kernel has these fixes.
>
> commit 1f85e6267caca44b30c54711652b0726fadbb131    tcp: do not send
> empty skb from tcp_write_xmit()
> commit 0c175da7b0378445f5ef53904247cfbfb87e0b78     tcp: prohibit
> TCP_REPAIR_OPTIONS if data was already sent

We have the first commit, but not the second.

Josh