Re: [BUG] KASAN: slab-use-after-free Read in slip_receive_buf

[Qingfang Deng]

Hi,

On 2026/8/25 23:27, Eric Dumazet wrote:
> On Tue, Aug 25, 2026 at 5:07 PM Jaeyoung Chung <jjy600901@xxxxxxxxx> wrote:
> > Hello,
> >
> > We found a "KASAN: slab-use-after-free Read in slip_receive_buf" on Linux v7.2.
> > The issue was found by our own race fuzzer. We have not analyzed the root cause,
> > so we do not have a proposed fix to offer.
> >
> > To reproduce the race reliably, we applied the delay patch below to the
> > kernel and ran the C reproducer as root inside an x86_64 QEMU guest. The
> > crash log we observed, the delay patch and the reproducer are all included
> > below.
> >
> > The following kernel config options are required to reproduce the issue:
> >      CONFIG_SLIP=y
> >      CONFIG_LEGACY_TIOCSTI=y
> >      CONFIG_UNIX98_PTYS=y
> >      CONFIG_TTY=y
> >      CONFIG_KASAN=y
> >
> > We hope this report is useful. Please let us know if any further
> > information would help.
> >
> > Reported-by: Eulgyu Kim <eulgyukim@xxxxxxxxx>
> > Reported-by: Jaeyoung Chung <jjy600901@xxxxxxxxx>
> This rings a bell; I had a local syzbot report for this issue a while back.
>
> I think we should remove slip_hangup().
ppp_async.c and ppp_synctty.c have the same anti-pattern. Should we 
remove theirs as well?