Re: [syzbot] [mm?] general protection fault in shmem_get_next_id
From: Andrew Morton
Date: Wed Apr 03 2024 - 21:33:49 EST
On Mon, 01 Apr 2024 23:58:20 -0700 syzbot <syzbot+05e63c0981a31f35f3fa@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> Hello,
Hello.
Seems that the new TMPFS_QUOTA code has blown up. Cc's added, thanks
for the report and the reproducer!
> syzbot found the following issue on:
>
> HEAD commit: fe46a7dd189e Merge tag 'sound-6.9-rc1' of git://git.kernel..
> git tree: upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=10c90795180000
> kernel config: https://syzkaller.appspot.com/x/.config?x=fe78468a74fdc3b7
> dashboard link: https://syzkaller.appspot.com/bug?extid=05e63c0981a31f35f3fa
> 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=17f51129180000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=150d3cee180000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/0f7abe4afac7/disk-fe46a7dd.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/82598d09246c/vmlinux-fe46a7dd.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/efa23788c875/bzImage-fe46a7dd.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+05e63c0981a31f35f3fa@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI
> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> CPU: 0 PID: 5070 Comm: syz-executor253 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> RIP: 0010:shmem_get_next_id+0x92/0x5c0 mm/shmem_quota.c:119
> Code: 04 db 49 8d 9c c6 90 02 00 00 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 f8 66 1b 00 48 8b 1b 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 df 66 1b 00 4c 8b 23 48 8d 5d 07
> RSP: 0018:ffffc900043a7be0 EFLAGS: 00010256
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8880266c8000
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000004
> RBP: ffffc900043a7d00 R08: ffffffff81dcdd47 R09: ffffffff822e7d5a
> R10: 0000000000000003 R11: ffffffff81dcdcf0 R12: 1ffff92000874fa0
> R13: ffff888022110000 R14: ffff888022110000 R15: dffffc0000000000
> FS: 0000555578677380(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020001000 CR3: 000000007a384000 CR4: 0000000000350ef0
> Call Trace:
> <TASK>
> dquot_get_next_dqblk+0x75/0x3a0 fs/quota/dquot.c:2705
> quota_getnextquota+0x2c7/0x6c0 fs/quota/quota.c:250
> __do_sys_quotactl_fd fs/quota/quota.c:1002 [inline]
> __se_sys_quotactl_fd+0x2a1/0x440 fs/quota/quota.c:973
> do_syscall_64+0xfd/0x240
> entry_SYSCALL_64_after_hwframe+0x6d/0x75
> RIP: 0033:0x7f5c0349b329
> Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffc39d71138 EFLAGS: 00000246 ORIG_RAX: 00000000000001bb
> RAX: ffffffffffffffda RBX: 0031656c69662f2e RCX: 00007f5c0349b329
> RDX: 0000000000000000 RSI: ffffffff80000901 RDI: 0000000000000003
> RBP: 00007f5c0350e610 R08: 0000000000000000 R09: 00007ffc39d71308
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
> R13: 00007ffc39d712f8 R14: 0000000000000001 R15: 0000000000000001
> </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:shmem_get_next_id+0x92/0x5c0 mm/shmem_quota.c:119
> Code: 04 db 49 8d 9c c6 90 02 00 00 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 f8 66 1b 00 48 8b 1b 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 df 66 1b 00 4c 8b 23 48 8d 5d 07
> RSP: 0018:ffffc900043a7be0 EFLAGS: 00010256
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8880266c8000
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000004
> RBP: ffffc900043a7d00 R08: ffffffff81dcdd47 R09: ffffffff822e7d5a
> R10: 0000000000000003 R11: ffffffff81dcdcf0 R12: 1ffff92000874fa0
> R13: ffff888022110000 R14: ffff888022110000 R15: dffffc0000000000
> FS: 0000555578677380(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020001000 CR3: 000000007a384000 CR4: 0000000000350ef0
> ----------------
> Code disassembly (best guess):
> 0: 04 db add $0xdb,%al
> 2: 49 8d 9c c6 90 02 00 lea 0x290(%r14,%rax,8),%rbx
> 9: 00
> a: 48 89 d8 mov %rbx,%rax
> d: 48 c1 e8 03 shr $0x3,%rax
> 11: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1)
> 16: 74 08 je 0x20
> 18: 48 89 df mov %rbx,%rdi
> 1b: e8 f8 66 1b 00 call 0x1b6718
> 20: 48 8b 1b mov (%rbx),%rbx
> 23: 48 89 d8 mov %rbx,%rax
> 26: 48 c1 e8 03 shr $0x3,%rax
> * 2a: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1) <-- trapping instruction
> 2f: 74 08 je 0x39
> 31: 48 89 df mov %rbx,%rdi
> 34: e8 df 66 1b 00 call 0x1b6718
> 39: 4c 8b 23 mov (%rbx),%r12
> 3c: 48 8d 5d 07 lea 0x7(%rbp),%rbx
>
>
> ---
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