[syzbot] [netfilter?] KMSAN: uninit-value in nf_flow_offload_ip_hook

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3e92c1e6cd87 Merge tag 'selinux-pr-20240402' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=135dbd3d180000
kernel config: https://syzkaller.appspot.com/x/.config?x=5112b3f484393436
dashboard link: https://syzkaller.appspot.com/bug?extid=b6f07e1c07ef40199081
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ac287f716705/disk-3e92c1e6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f04f8cb0bdc6/vmlinux-3e92c1e6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8eb9003da40/bzImage-3e92c1e6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b6f07e...@syzkaller.appspotmail.com

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BUG: KMSAN: uninit-value in nf_flow_skb_encap_protocol net/netfilter/nf_flow_table_ip.c:290 [inline]
BUG: KMSAN: uninit-value in nf_flow_offload_lookup net/netfilter/nf_flow_table_ip.c:352 [inline]
BUG: KMSAN: uninit-value in nf_flow_offload_ip_hook+0x79a/0x3e40 net/netfilter/nf_flow_table_ip.c:424
nf_flow_skb_encap_protocol net/netfilter/nf_flow_table_ip.c:290 [inline]
nf_flow_offload_lookup net/netfilter/nf_flow_table_ip.c:352 [inline]
nf_flow_offload_ip_hook+0x79a/0x3e40 net/netfilter/nf_flow_table_ip.c:424
nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
nf_hook_slow+0xf2/0x3f0 net/netfilter/core.c:626
nf_hook_ingress include/linux/netfilter_netdev.h:34 [inline]
nf_ingress net/core/dev.c:5318 [inline]
__netif_receive_skb_core+0x430b/0x6190 net/core/dev.c:5406
__netif_receive_skb_one_core net/core/dev.c:5536 [inline]
__netif_receive_skb+0xca/0xa00 net/core/dev.c:5652
netif_receive_skb_internal net/core/dev.c:5738 [inline]
netif_receive_skb+0x58/0x660 net/core/dev.c:5798
tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1549
tun_get_user+0x5566/0x69e0 drivers/net/tun.c:2002
tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
call_write_iter include/linux/fs.h:2108 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xb63/0x1520 fs/read_write.c:590
ksys_write+0x20f/0x4c0 fs/read_write.c:643
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x93/0xe0 fs/read_write.c:652
do_syscall_64+0xd5/0x1f0
entry_SYSCALL_64_after_hwframe+0x72/0x7a

Uninit was created at:
__alloc_pages+0x9d6/0xe70 mm/page_alloc.c:4598
alloc_pages_mpol+0x299/0x990 mm/mempolicy.c:2264
alloc_pages+0x1bf/0x1e0 mm/mempolicy.c:2335
skb_page_frag_refill+0x2bf/0x7c0 net/core/sock.c:2921
tun_build_skb drivers/net/tun.c:1679 [inline]
tun_get_user+0x1258/0x69e0 drivers/net/tun.c:1819
tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
call_write_iter include/linux/fs.h:2108 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xb63/0x1520 fs/read_write.c:590
ksys_write+0x20f/0x4c0 fs/read_write.c:643
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x93/0xe0 fs/read_write.c:652
do_syscall_64+0xd5/0x1f0
entry_SYSCALL_64_after_hwframe+0x72/0x7a

CPU: 0 PID: 5636 Comm: syz-executor.0 Not tainted 6.9.0-rc2-syzkaller-00042-g3e92c1e6cd87 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
=====================================================


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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: c85af715cac0 Merge tag 'vboxsf-v6.9-1' of git://git.kernel..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1123c615180000

kernel config: https://syzkaller.appspot.com/x/.config?x=5112b3f484393436
dashboard link: https://syzkaller.appspot.com/bug?extid=b6f07e1c07ef40199081
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16960955180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11cfc58d180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6741d41720b3/disk-c85af715.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1783406dda64/vmlinux-c85af715.xz
kernel image: https://storage.googleapis.com/syzbot-assets/53eeb4798ae1/bzImage-c85af715.xz

CPU: 0 PID: 5020 Comm: syz-executor108 Not tainted 6.9.0-rc2-syzkaller-00080-gc85af715cac0 #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
=====================================================


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