Messages in this thread | | | Date | Mon, 8 Apr 2024 22:30:21 -0700 | Subject | Re: [syzbot] [bpf?] KMSAN: uninit-value in strnchr | From | Martin KaFai Lau <> |
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On 3/7/24 12:30 AM, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 04b8076df253 Merge tag 'firewire-fixes-6.8-rc7' of git://g.. > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=10bb9306180000 > kernel config: https://syzkaller.appspot.com/x/.config?x=80c7a82a572c0de3 > dashboard link: https://syzkaller.appspot.com/bug?extid=9b8be5e35747291236c8 > 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=11093316180000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15a53082180000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/a4610b1ff2a7/disk-04b8076d.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/991e9d902d39/vmlinux-04b8076d.xz > kernel image: https://storage.googleapis.com/syzbot-assets/a5b8e8e98121/bzImage-04b8076d.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+9b8be5e35747291236c8@syzkaller.appspotmail.com > > ===================================================== > BUG: KMSAN: uninit-value in strnchr+0x90/0xd0 lib/string.c:388 > strnchr+0x90/0xd0 lib/string.c:388 > bpf_bprintf_prepare+0x1c2/0x23b0 kernel/bpf/helpers.c:829 > ____bpf_trace_printk kernel/trace/bpf_trace.c:385 [inline] > bpf_trace_printk+0xec/0x3e0 kernel/trace/bpf_trace.c:375 > ___bpf_prog_run+0x2180/0xdb80 kernel/bpf/core.c:1986 > __bpf_prog_run32+0xb2/0xe0 kernel/bpf/core.c:2225
This is the same as the dev_map_lookup_elem report when running in interpreter mode. It loads a different program to call bpf_trace_printk instead.
0: (6a) *(u16 *)(r10 -8) = 628106613 1: (bf) r1 = r10 2: (07) r1 += -8 3: (b7) r2 = 5 4: (bf) r3 = r1 5: (85) call bpf_trace_printk#-315920 6: (b7) r0 = 0 7: (95) exit
#syz dup: [syzbot] [bpf?] [net?] KMSAN: uninit-value in dev_map_lookup_elem
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