Re: Use of uninit value in inet_bind2_bucket_find

[Martin KaFai Lau <martin.lau@linux.dev>]

On 9/19/22 6:41 AM, Alexander Potapenko wrote:
> Hi Joanne, Jakub et al.,
> 
> When building next-20220919 with KMSAN I am seeing the following error
> at boot time:
> 
> =====================================================
> BUG: KMSAN: uninit-value in inet_bind2_bucket_find+0x71f/0x790
> net/ipv4/inet_hashtables.c:827
>   inet_bind2_bucket_find+0x71f/0x790 net/ipv4/inet_hashtables.c:827
>   inet_csk_get_port+0x2415/0x32e0 net/ipv4/inet_connection_sock.c:529
>   __inet6_bind+0x1474/0x1a20 net/ipv6/af_inet6.c:406
>   inet6_bind+0x176/0x360 net/ipv6/af_inet6.c:465
>   __sys_bind+0x5b3/0x750 net/socket.c:1776
>   __do_sys_bind net/socket.c:1787
>   __se_sys_bind net/socket.c:1785
>   __x64_sys_bind+0x8d/0xe0 net/socket.c:1785
>   do_syscall_x64 arch/x86/entry/common.c:50
>   do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
>   entry_SYSCALL_64_after_hwframe+0x63/0xcd ??:?
> 
> Uninit was created at:
>   slab_post_alloc_hook+0x156/0xb40 mm/slab.h:759
>   slab_alloc_node mm/slub.c:3331
>   slab_alloc mm/slub.c:3339
>   __kmem_cache_alloc_lru mm/slub.c:3346
>   kmem_cache_alloc+0x47e/0x9f0 mm/slub.c:3355
>   inet_bind2_bucket_create+0x4b/0x3b0 net/ipv4/inet_hashtables.c:128
>   inet_csk_get_port+0x2513/0x32e0 net/ipv4/inet_connection_sock.c:533
>   __inet_bind+0xbd2/0x1040 net/ipv4/af_inet.c:525
>   inet_bind+0x184/0x360 net/ipv4/af_inet.c:456
>   __sys_bind+0x5b3/0x750 net/socket.c:1776
>   __do_sys_bind net/socket.c:1787
>   __se_sys_bind net/socket.c:1785
>   __x64_sys_bind+0x8d/0xe0 net/socket.c:1785
>   do_syscall_x64 arch/x86/entry/common.c:50
>   do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
>   entry_SYSCALL_64_after_hwframe+0x63/0xcd ??:?
> 
> CPU: 3 PID: 5983 Comm: sshd Not tainted 6.0.0-rc6-next-20220919 #211
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> 1.16.0-debian-1.16.0-4 04/01/2014
> =====================================================
> 
> I think this is related to "net: Add a bhash2 table hashed by port and
> address", could you please take a look?
> This error is not reported on v6.0-rc5 (note that KMSAN only exists in
> -next and as a v6.0-rc5 fork at https://github.com/google/kmsan).

Hi Alex, thanks for the report.

I have posted a fix [0].  I have problem getting kmsan kernel to boot. 
Could you help to give the patch a try ?  Thanks.

[0]: https://lore.kernel.org/netdev/20220927002544.3381205-1-kafai@fb.com/