Re: [syzbot] kernel panic: panic_on_warn set (3)

From: Marco Elver
Date: Fri Sep 10 2021 - 03:34:40 EST


#syz invalid

Corrupt report. (syzbot somehow failed to parse the report?)

Same use-after-free bug as this:
https://lore.kernel.org/all/000000000000d6b66705cb2fffd4@xxxxxxxxxx/T/#u
which still seems unfixed...

On Fri, 10 Sept 2021 at 02:34, syzbot
<syzbot+8d41ad9c88279d71f7c9@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: ac08b1c68d1b Merge tag 'pci-v5.15-changes' of git://git.ke..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=16144a63300000
> kernel config: https://syzkaller.appspot.com/x/.config?x=16e23f04679ec35e
> dashboard link: https://syzkaller.appspot.com/bug?extid=8d41ad9c88279d71f7c9
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
> userspace arch: i386
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=136aedb5300000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+8d41ad9c88279d71f7c9@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> handle drivers/base/devtmpfs.c:382 [inline]
> devtmpfs_work_loop drivers/base/devtmpfs.c:395 [inline]
> devtmpfsd+0x1b9/0x2a3 drivers/base/devtmpfs.c:437
> kthread+0x3e5/0x4d0 kernel/kthread.c:319
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> ==================================================================
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 22 Comm: kdevtmpfs Not tainted 5.14.0-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:88 [inline]
> dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
> panic+0x2b0/0x6dd kernel/panic.c:232
> kfence_report_error.cold+0x304/0xa56 mm/kfence/report.c:264
> kfence_handle_page_fault+0x203/0x630 mm/kfence/core.c:880
> page_fault_oops+0x1c5/0x6b0 arch/x86/mm/fault.c:686
> kernelmode_fixup_or_oops+0x219/0x280 arch/x86/mm/fault.c:755
> __bad_area_nosemaphore+0x36d/0x400 arch/x86/mm/fault.c:801
> do_kern_addr_fault+0x5b/0x70 arch/x86/mm/fault.c:1200
> handle_page_fault arch/x86/mm/fault.c:1473 [inline]
> exc_page_fault+0x155/0x180 arch/x86/mm/fault.c:1531
> asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:568
> RIP: 0010:kvm_fastop_exception+0xf6a/0x1058
> Code: d3 ed e9 ef d4 6e f8 49 8d 0e 48 83 e1 f8 4c 8b 21 41 8d 0e 83 e1 07 c1 e1 03 49 d3 ec e9 45 e2 6e f8 49 8d 4d 00 48 83 e1 f8 <4c> 8b 21 41 8d 4d 00 83 e1 07 c1 e1 03 49 d3 ec e9 35 ec 6e f8 bd
> RSP: 0018:ffffc90000dcfae8 EFLAGS: 00010282
> RAX: 0000003361736376 RBX: ffff88806f1e3068 RCX: ffff88823bd14020
> RDX: ffffed100de3c614 RSI: 0000000000000005 RDI: 0000000000000007
> RBP: 0000000000000005 R08: 0000000000000000 R09: ffff88806f1e3098
> R10: ffffed100de3c613 R11: 0000000000000000 R12: ffff88823bd14020
> R13: ffff88823bd14020 R14: ffff88806f1e3098 R15: dffffc0000000000
> d_lookup+0xd8/0x170 fs/dcache.c:2370
> lookup_dcache+0x1e/0x130 fs/namei.c:1520
> __lookup_hash+0x29/0x180 fs/namei.c:1543
> kern_path_locked+0x17e/0x320 fs/namei.c:2567
> handle_remove+0xa2/0x5fe drivers/base/devtmpfs.c:312
> handle drivers/base/devtmpfs.c:382 [inline]
> devtmpfs_work_loop drivers/base/devtmpfs.c:395 [inline]
> devtmpfsd+0x1b9/0x2a3 drivers/base/devtmpfs.c:437
> kthread+0x3e5/0x4d0 kernel/kthread.c:319
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> Kernel Offset: disabled
> ----------------
> Code disassembly (best guess):
> 0: d3 ed shr %cl,%ebp
> 2: e9 ef d4 6e f8 jmpq 0xf86ed4f6
> 7: 49 8d 0e lea (%r14),%rcx
> a: 48 83 e1 f8 and $0xfffffffffffffff8,%rcx
> e: 4c 8b 21 mov (%rcx),%r12
> 11: 41 8d 0e lea (%r14),%ecx
> 14: 83 e1 07 and $0x7,%ecx
> 17: c1 e1 03 shl $0x3,%ecx
> 1a: 49 d3 ec shr %cl,%r12
> 1d: e9 45 e2 6e f8 jmpq 0xf86ee267
> 22: 49 8d 4d 00 lea 0x0(%r13),%rcx
> 26: 48 83 e1 f8 and $0xfffffffffffffff8,%rcx
> * 2a: 4c 8b 21 mov (%rcx),%r12 <-- trapping instruction
> 2d: 41 8d 4d 00 lea 0x0(%r13),%ecx
> 31: 83 e1 07 and $0x7,%ecx
> 34: c1 e1 03 shl $0x3,%ecx
> 37: 49 d3 ec shr %cl,%r12
> 3a: e9 35 ec 6e f8 jmpq 0xf86eec74
> 3f: bd .byte 0xbd
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
>
> syzbot will keep track of this issue. See:
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> syzbot can test patches for this issue, for details see:
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