[syzbot] [net?] [virt?] upstream test error: KMSAN: uninit-value in receive_buf

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 56fb6f92854f Merge tag 'drm-next-2024-05-25' of https://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=157a5462980000
kernel config: https://syzkaller.appspot.com/x/.config?x=1b6c22bca89a3565
dashboard link: https://syzkaller.appspot.com/bug?extid=799fbb6d9e02a7a1d62b
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/39a256e13faa/disk-56fb6f92.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d4ecc47a8198/vmlinux-56fb6f92.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0d37bfdfb0ca/bzImage-56fb6f92.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+799fbb...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in receive_mergeable drivers/net/virtio_net.c:1839 [inline]
BUG: KMSAN: uninit-value in receive_buf+0x25e3/0x5fd0 drivers/net/virtio_net.c:1955
receive_mergeable drivers/net/virtio_net.c:1839 [inline]
receive_buf+0x25e3/0x5fd0 drivers/net/virtio_net.c:1955
virtnet_receive drivers/net/virtio_net.c:2259 [inline]
virtnet_poll+0xd1c/0x23c0 drivers/net/virtio_net.c:2362
__napi_poll+0xe7/0x980 net/core/dev.c:6721
napi_poll net/core/dev.c:6790 [inline]
net_rx_action+0x82a/0x1850 net/core/dev.c:6906
handle_softirqs+0x1ce/0x800 kernel/softirq.c:554
__do_softirq kernel/softirq.c:588 [inline]
invoke_softirq kernel/softirq.c:428 [inline]
__irq_exit_rcu+0x68/0x120 kernel/softirq.c:637
irq_exit_rcu+0x12/0x20 kernel/softirq.c:649
common_interrupt+0x94/0xa0 arch/x86/kernel/irq.c:278
asm_common_interrupt+0x2b/0x40 arch/x86/include/asm/idtentry.h:693
kmsan_get_shadow_origin_ptr+0x86/0xb0 mm/kmsan/shadow.c:116
get_shadow_origin_ptr mm/kmsan/instrumentation.c:36 [inline]
__msan_metadata_ptr_for_load_4+0x24/0x40 mm/kmsan/instrumentation.c:91
stack_trace_consume_entry+0x16f/0x1e0 kernel/stacktrace.c:94
arch_stack_walk+0x1ca/0x2d0 arch/x86/kernel/stacktrace.c:27
stack_trace_save+0xaa/0xe0 kernel/stacktrace.c:122
kmsan_save_stack_with_flags mm/kmsan/core.c:74 [inline]
kmsan_internal_poison_memory+0x49/0x90 mm/kmsan/core.c:58
kmsan_slab_alloc+0xdf/0x160 mm/kmsan/hooks.c:68
slab_post_alloc_hook mm/slub.c:3946 [inline]
slab_alloc_node mm/slub.c:4000 [inline]
__do_kmalloc_node mm/slub.c:4120 [inline]
__kmalloc_noprof+0x660/0xf30 mm/slub.c:4134
kmalloc_noprof include/linux/slab.h:664 [inline]
tomoyo_realpath_from_path+0x104/0xaa0 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_check_open_permission+0x1ef/0xc50 security/tomoyo/file.c:771
tomoyo_file_open+0x271/0x360 security/tomoyo/tomoyo.c:334
security_file_open+0x9a/0xc60 security/security.c:2962
do_dentry_open+0x5b1/0x22b0 fs/open.c:942
vfs_open+0x49/0x60 fs/open.c:1089
do_open fs/namei.c:3650 [inline]
path_openat+0x4ab0/0x5b70 fs/namei.c:3807
do_filp_open+0x20e/0x590 fs/namei.c:3834
do_sys_openat2+0x1bf/0x2f0 fs/open.c:1405
do_sys_open fs/open.c:1420 [inline]
__do_sys_openat fs/open.c:1436 [inline]
__se_sys_openat fs/open.c:1431 [inline]
__x64_sys_openat+0x2a1/0x310 fs/open.c:1431
x64_sys_call+0x128b/0x3b90 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
__alloc_pages_noprof+0x9d6/0xe70 mm/page_alloc.c:4683
alloc_pages_mpol_noprof+0x299/0x990 mm/mempolicy.c:2265
alloc_pages_noprof+0x1bf/0x1e0 mm/mempolicy.c:2336
skb_page_frag_refill+0x2bf/0x7c0 net/core/sock.c:2920
virtnet_rq_alloc+0x43/0xbb0 drivers/net/virtio_net.c:882
add_recvbuf_mergeable drivers/net/virtio_net.c:2110 [inline]
try_fill_recv+0x3f0/0x2f50 drivers/net/virtio_net.c:2155
virtnet_open+0x1cc/0xb00 drivers/net/virtio_net.c:2434
__dev_open+0x546/0x6f0 net/core/dev.c:1472
__dev_change_flags+0x309/0x9a0 net/core/dev.c:8780
dev_change_flags+0x8e/0x1d0 net/core/dev.c:8852
devinet_ioctl+0x13ec/0x22c0 net/ipv4/devinet.c:1177
inet_ioctl+0x4bd/0x6d0 net/ipv4/af_inet.c:1003
sock_do_ioctl+0xb7/0x540 net/socket.c:1222
sock_ioctl+0x727/0xd70 net/socket.c:1341
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl+0x261/0x450 fs/ioctl.c:893
__x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:893
x64_sys_call+0x18c0/0x3b90 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 PID: 4772 Comm: ssh-keygen Not tainted 6.9.0-syzkaller-12277-g56fb6f92854f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
=====================================================


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[Tetsuo Handa]

Bisection reached commit f9dac92ba908 ("virtio_ring: enable premapped mode
whatever use_dma_api").

[Tetsuo Handa]

On 2024/06/18 10:27, Xuan Zhuo wrote:
> Maybe this patch can fix this issue:
>
> http://lore.kernel.org/all/20240606111345....@linux.alibaba.com

Yes, thank you.

#syz fix: virtio_ring: fix KMSAN error for premapped mode

[Xuan Zhuo]

Maybe this patch can fix this issue:

http://lore.kernel.org/all/20240606111345....@linux.alibaba.com

Thanks.