[BUG] general protection fault in security_path_post_mknod

[Farhad Alemi]

Hi Paul,

Upon our run, the patched kernel (proposed patch applied on
28924df2a08f) no longer panics on the reproducer.

Thanks,

On Fri, Aug 28, 2026 at 11:48 AM Paul Moore <paul at paul-moore.com> wrote:
>
> On Fri, Aug 28, 2026 at 2:11 AM Farhad Alemi <farhad.alemi at berkeley.edu> wrote:
> >
> > Hello,
> >
> > As part of the kernel research at ASU's SEFCOM
> > lab, we hit the crash below. Crash reports can be found here:
> >
> >   https://github.com/farhad-alemi/public_bug_reports/tree/main/178-general-protection-fault-in-security-path-post-mknod/
> >
> >   Oops: general protection fault, probably for non-canonical address
> > 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
> >   KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> >   RIP: 0010:security_path_post_mknod+0x49/0x1e0 security/security.c:1430
> >   Call Trace:
> >    security_path_post_mknod+0x49/0x1e0 security/security.c:1430
> >    filename_mknodat+0x40e/0x660 fs/namei.c:5172
> >    __do_sys_mknod fs/namei.c:5207 [inline]
> >    __se_sys_mknod+0x3a/0x150 fs/namei.c:5204
> >    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> >    do_syscall_64+0x146/0x480 arch/x86/entry/syscall_64.c:94
> >    entry_SYSCALL_64_after_hwframe+0x77/0x7f
> >
> > Our reproducer.c is available upon request.
> >
> > Happy to test a patch if that would help.
>
> Hi Farhad, thanks for the report.  Do you think you can diagnose the
> problem and submit a patch?  Bug reports are always welcome, but as
> you may have noticed, we have plenty of those at the moment.  People
> willing to not only identify problems but fix them too is something we
> are running a bit short on at the moment ;)
>
> --
> paul-moore.com