Re: [PATCH net-next] ipv6: add debug checks in fib6_info_release()

[Kui-Feng Lee <sinquersw@gmail.com>]

On 12/7/23 10:10, Eric Dumazet wrote:
> On Thu, Dec 7, 2023 at 7:06 PM Kui-Feng Lee <sinquersw@gmail.com> wrote:
> 
>> Do you happen to have a test program that can reproduce it?
> 
> syzbot has a repro, let me release the bug.
> 
> Of course syzbot bisection points to my last patch.

I just looked into the code.
The origin issue mentioned at the thread head should be something
related to a GC change I made. But, the warnings you added doesn't
catch the the error correctly.  According to your stacktrace


 > ip6_route_add+0x26/0x1f0 net/ipv6/route.c:3843
 > ipv6_route_ioctl+0x3ff/0x590 net/ipv6/route.c:4467
 > inet6_ioctl+0x265/0x2b0 net/ipv6/af_inet6.c:575
 > sock_do_ioctl+0x113/0x270 net/socket.c:1220
 > sock_ioctl+0x22e/0x6b0 net/socket.c:1339
 > vfs_ioctl fs/ioctl.c:51 [inline]
 > __do_sys_ioctl fs/ioctl.c:871 [inline]
 > __se_sys_ioctl fs/ioctl.c:857 [inline]
 > __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
 > do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 > do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
 > entry_SYSCALL_64_after_hwframe+0x63/0x6b

and warning messages you provided

 > WARNING: CPU: 0 PID: 5059 at include/net/ip6_fib.h:332
 > fib6_info_release include/net/ip6_fib.h:332 [inline]
 > WARNING: CPU: 0 PID: 5059 at include/net/ip6_fib.h:332
 > ip6_route_info_create+0x1a1a/0x1f10 net/ipv6/route.c:3829

It takes place in ip6_route_info_create() to do error handling.
It can be fib6_has_expires() in fib6_info_release() in this case.