On 3/28/24 7:59 PM, syzbot wrote:
syzbot has found a reproducer for the following issue on:
HEAD commit: 8d025e2092e2 Merge tag 'erofs-for-6.9-rc2-fixes' of git://..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=10f2ffe6180000
kernel config: https://syzkaller.appspot.com/x/.config?x=e2599baf258ef795
dashboard link: https://syzkaller.appspot.com/bug?extid=8ac8b7b2292ea867a162
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=15b3ac29180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=160153c9180000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5ccde1a19e22/disk-8d025e20.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/45420817e7d9/vmlinux-8d025e20.xz
kernel image: https://storage.googleapis.com/syzbot-assets/354bdafd8c8f/bzImage-8d025e20.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8ac8b7b2292ea867a162@xxxxxxxxxxxxxxxxxxxxxxxxx
=====================================================
BUG: KMSAN: uninit-value in __bpf_strtoull+0x245/0x5b0 kernel/bpf/helpers.c:465
__bpf_strtoull+0x245/0x5b0 kernel/bpf/helpers.c:465
__bpf_strtoll kernel/bpf/helpers.c:504 [inline]
____bpf_strtol kernel/bpf/helpers.c:525 [inline]
bpf_strtol+0x7c/0x270 kernel/bpf/helpers.c:519
___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997
__bpf_prog_run96+0xb5/0xe0 kernel/bpf/core.c:2236
This should be similar to the other KMSAN reports on the interpreter using
the uninit stack in the map_lookup/delete_elem helpers. The bpf prog used
in this C reproducer:
0: (18) r0 = 0x0
2: (b7) r8 = 0
3: (7b) *(u64 *)(r10 -72) = r8
4: (b7) r8 = 0
5: (7b) *(u64 *)(r10 -16) = r8
6: (bf) r1 = r10
7: (07) r1 += -8
^^^^^^^^
8: (bf) r4 = r10
9: (07) r4 += -16
10: (b7) r2 = 8
11: (18) r3 = map[id:68][0]+0
13: (b7) r3 = 0
14: (85) call bpf_strtol#896752
15: (95) exit
#syz fix: bpf: Mark bpf prog stack with kmsan_unposion_memory in interpreter mode
