Messages in this thread | | | From | Dmitry Vyukov <> | Date | Mon, 20 Apr 2020 20:12:39 +0200 | Subject | Re: KMSAN: uninit-value in audit_log_vformat (2) |
| |
On Mon, Apr 20, 2020 at 6:29 PM Paul Moore <paul@paul-moore.com> wrote: > > On Mon, Apr 20, 2020 at 1:35 AM syzbot > <syzbot+49e69b4d71a420ceda3e@syzkaller.appspotmail.com> wrote: > > > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: 5356842d [EXPERIMENTAL] kmsan: eagerly allocate shadow at .. > > git tree: https://github.com/google/kmsan.git master > > console output: https://syzkaller.appspot.com/x/log.txt?x=12f06720100000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=a5915107b3106aaa > > dashboard link: https://syzkaller.appspot.com/bug?extid=49e69b4d71a420ceda3e > > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) > > userspace arch: i386 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133b5dabe00000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=143e1610100000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+49e69b4d71a420ceda3e@syzkaller.appspotmail.com > > > > ===================================================== > > BUG: KMSAN: uninit-value in string_nocheck lib/vsprintf.c:608 [inline] > > BUG: KMSAN: uninit-value in string+0x522/0x690 lib/vsprintf.c:689 > > CPU: 1 PID: 8854 Comm: syz-executor694 Not tainted 5.6.0-rc7-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:77 [inline] > > dump_stack+0x1c9/0x220 lib/dump_stack.c:118 > > kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118 > > __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215 > > string_nocheck lib/vsprintf.c:608 [inline] > > string+0x522/0x690 lib/vsprintf.c:689 > > vsnprintf+0x207d/0x31b0 lib/vsprintf.c:2574 > > Are there any ongoing problems with [vsn]printf() in the kernel at the > moment with syzbot? > > I ask because on first look I'm not seeing any obvious problems in the > audit portion of this code path.
None I am aware of. Alex? Can it be related to data_len==0? I don't see any obvious checks for this. And in that case will 0-terminate out-of-bounds (at offset -1?) and print potentially uninit data. But I looked at the code only very briefly so potentially I am totally wrong.
> > audit_log_vformat+0x583/0xcd0 kernel/audit.c:1858 > > audit_log_format+0x220/0x260 kernel/audit.c:1892 > > audit_receive_msg kernel/audit.c:1344 [inline] > > audit_receive+0x18a4/0x6d50 kernel/audit.c:1515 > > netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline] > > netlink_unicast+0xf9e/0x1100 net/netlink/af_netlink.c:1329 > > netlink_sendmsg+0x1246/0x14d0 net/netlink/af_netlink.c:1918 > > sock_sendmsg_nosec net/socket.c:652 [inline] > > sock_sendmsg net/socket.c:672 [inline] > > ____sys_sendmsg+0x12b6/0x1350 net/socket.c:2345 > > ___sys_sendmsg net/socket.c:2399 [inline] > > __sys_sendmsg+0x451/0x5f0 net/socket.c:2432 > > __compat_sys_sendmsg net/compat.c:642 [inline] > > __do_compat_sys_sendmsg net/compat.c:649 [inline] > > __se_compat_sys_sendmsg net/compat.c:646 [inline] > > __ia32_compat_sys_sendmsg+0xed/0x130 net/compat.c:646 > > do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline] > > do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410 > > entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139 > > RIP: 0023:0xf7fa0d99 > > Code: 90 e8 0b 00 00 00 f3 90 0f ae e8 eb f9 8d 74 26 00 89 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 > > RSP: 002b:00000000ffb27c7c EFLAGS: 00000246 ORIG_RAX: 0000000000000172 > > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000200002c0 > > RDX: 0000000000000000 RSI: 00000000080ea078 RDI: 00000000ffb27cd0 > > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > > > Uninit was created at: > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline] > > kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127 > > kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:82 > > slab_alloc_node mm/slub.c:2801 [inline] > > __kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4420 > > __kmalloc_reserve net/core/skbuff.c:142 [inline] > > __alloc_skb+0x2fd/0xac0 net/core/skbuff.c:210 > > alloc_skb include/linux/skbuff.h:1081 [inline] > > netlink_alloc_large_skb net/netlink/af_netlink.c:1175 [inline] > > netlink_sendmsg+0x7d3/0x14d0 net/netlink/af_netlink.c:1893 > > sock_sendmsg_nosec net/socket.c:652 [inline] > > sock_sendmsg net/socket.c:672 [inline] > > ____sys_sendmsg+0x12b6/0x1350 net/socket.c:2345 > > ___sys_sendmsg net/socket.c:2399 [inline] > > __sys_sendmsg+0x451/0x5f0 net/socket.c:2432 > > __compat_sys_sendmsg net/compat.c:642 [inline] > > __do_compat_sys_sendmsg net/compat.c:649 [inline] > > __se_compat_sys_sendmsg net/compat.c:646 [inline] > > __ia32_compat_sys_sendmsg+0xed/0x130 net/compat.c:646 > > do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline] > > do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410 > > entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139 > > ===================================================== > > -- > paul moore > www.paul-moore.com > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/CAHC9VhTZ_itetT4cx32vW3A79tb76dzjaBC_0S8Y_%3DDcEBL2nw%40mail.gmail.com.
| |