[syzbot] KMSAN: uninit-value in bpf_prog_run_generic_xdp

syzbot
2022-11-18T11:39:52Z

Hello,

syzbot found the following issue on:

HEAD commit: cb231e2f67ec fs: more fsdata fixes
git tree: https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=14ef6401880000
kernel config: https://syzkaller.appspot.com/x/.config?x=dc6d7125db95a828
dashboard link: https://syzkaller.appspot.com/bug?extid=0e6ddb1ef80986bdfe64
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project.git 610139d2d9ce6746b3c617fb3e2f7886272d26ff), GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: i386

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6eabbc575a06/disk-cb231e2f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/01e99c04e1d7/vmlinux-cb231e2f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/67893482166a/bzImage-cb231e2f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0e6ddb1ef80986bdfe64@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in bpf_prog_run_generic_xdp+0x13ff/0x1a30 net/core/dev.c:4782
bpf_prog_run_generic_xdp+0x13ff/0x1a30 net/core/dev.c:4782
netif_receive_generic_xdp+0x639/0x910 net/core/dev.c:4845
do_xdp_generic net/core/dev.c:4904 [inline]
__netif_receive_skb_core+0x290f/0x6360 net/core/dev.c:5310
__netif_receive_skb_one_core net/core/dev.c:5487 [inline]
__netif_receive_skb+0xc8/0x5d0 net/core/dev.c:5603
process_backlog+0x45a/0x890 net/core/dev.c:5931
__napi_poll+0xe6/0x920 net/core/dev.c:6498
napi_poll net/core/dev.c:6565 [inline]
net_rx_action+0x9e8/0x1a20 net/core/dev.c:6676
__do_softirq+0x1c5/0x7b9 kernel/softirq.c:571
invoke_softirq+0x8f/0x100 kernel/softirq.c:445
__irq_exit_rcu+0x5a/0x110 kernel/softirq.c:650
irq_exit_rcu+0xe/0x10 kernel/softirq.c:662
sysvec_apic_timer_interrupt+0x9a/0xc0 arch/x86/kernel/apic/apic.c:1107
asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:649
kmsan_get_shadow_origin_ptr+0x34/0xa0 mm/kmsan/shadow.c:97
get_shadow_origin_ptr mm/kmsan/instrumentation.c:36 [inline]
__msan_metadata_ptr_for_load_8+0x20/0x30 mm/kmsan/instrumentation.c:78
unwind_get_return_address_ptr+0x97/0xc0 arch/x86/kernel/unwind_frame.c:28
update_stack_state+0x177/0x1e0 arch/x86/kernel/unwind_frame.c:251
unwind_next_frame+0x119/0x360 arch/x86/kernel/unwind_frame.c:315
arch_stack_walk+0x1b9/0x280 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xb2/0x100 kernel/stacktrace.c:122
kmsan_save_stack_with_flags mm/kmsan/core.c:75 [inline]
kmsan_internal_poison_memory+0x45/0x90 mm/kmsan/core.c:60
kmsan_slab_free+0xcd/0x130 mm/kmsan/hooks.c:90
slab_free_hook mm/slub.c:1694 [inline]
slab_free_freelist_hook mm/slub.c:1750 [inline]
slab_free mm/slub.c:3661 [inline]
kmem_cache_free+0x365/0xdb0 mm/slub.c:3683
security_file_free+0x15d/0x1a0 security/security.c:1548
file_free fs/file_table.c:56 [inline]
__fput+0xbed/0xea0 fs/file_table.c:333
____fput+0x1a/0x20 fs/file_table.c:348
task_work_run+0x229/0x2c0 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0x2a9/0x320 kernel/entry/common.c:171
exit_to_user_mode_prepare+0x16e/0x220 kernel/entry/common.c:203
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x23/0x40 kernel/entry/common.c:296
__do_fast_syscall_32+0xb1/0x100 arch/x86/entry/common.c:181
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
entry_SYSENTER_compat_after_hwframe+0x70/0x82

Uninit was created at:
slab_post_alloc_hook mm/slab.h:742 [inline]
slab_alloc_node mm/slub.c:3398 [inline]
__kmem_cache_alloc_node+0x6ee/0xc90 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc_node_track_caller+0x117/0x3d0 mm/slab_common.c:975
kmalloc_reserve net/core/skbuff.c:437 [inline]
pskb_expand_head+0x23d/0x1970 net/core/skbuff.c:1832
netif_receive_generic_xdp+0x4c6/0x910 net/core/dev.c:4837
do_xdp_generic net/core/dev.c:4904 [inline]
__netif_receive_skb_core+0x290f/0x6360 net/core/dev.c:5310
__netif_receive_skb_one_core net/core/dev.c:5487 [inline]
__netif_receive_skb+0xc8/0x5d0 net/core/dev.c:5603
process_backlog+0x45a/0x890 net/core/dev.c:5931
__napi_poll+0xe6/0x920 net/core/dev.c:6498
napi_poll net/core/dev.c:6565 [inline]
net_rx_action+0x9e8/0x1a20 net/core/dev.c:6676
__do_softirq+0x1c5/0x7b9 kernel/softirq.c:571

CPU: 0 PID: 3506 Comm: syz-executor.2 Tainted: G W 6.1.0-rc4-syzkaller-62821-gcb231e2f67ec #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
=====================================================

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