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general protection fault in bfs_get_block (2)

Status: fixed on 2024/01/30 15:47
Subsystems: bfs
[Documentation on labels]
Reported-by: syzbot+dc6ed11a88fb40d6e184@syzkaller.appspotmail.com
Fix commit: 6f861765464f fs: Block writes to mounted block devices
First crash: 157d, last: 134d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: fixed by (bisect log) :
commit 6f861765464f43a71462d52026fbddfc858239a5
Author: Jan Kara <jack@suse.cz>
Date: Wed Nov 1 17:43:10 2023 +0000

  fs: Block writes to mounted block devices

  
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[syzbot] [bfs?] general protection fault in bfs_get_block (2) 1 (5) 2024/01/16 09:24
[PATCH] bfs: Fix null pointer dereference in bfs_move_block 1 (1) 2023/11/26 23:39
▶ ▼ Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in bfs_get_block bfs 2 408d 444d 0/26 auto-obsoleted due to no activity on 2023/07/13 12:29
linux-6.1 general protection fault in bfs_get_block origin:upstream C 1 19d 391d 0/3 upstream: reported C repro on 2023/04/02 00:46
▶ ▼ Last patch testing requests (3)
Created Duration User Patch Repo Result
2023/12/05 16:47 15m retest repro upstream report log
2023/11/26 23:24 37m yuran.pereira@hotmail.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master report log
2023/11/26 22:41 50m yuran.pereira@hotmail.com https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master report log

Sample crash report:
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
CPU: 1 PID: 5059 Comm: syz-executor306 Not tainted 6.7.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
RIP: 0010:bfs_move_block fs/bfs/file.c:42 [inline]
RIP: 0010:bfs_move_blocks fs/bfs/file.c:56 [inline]
RIP: 0010:bfs_get_block+0x3b2/0xeb0 fs/bfs/file.c:125
Code: a8 ff 48 8d 7d 20 48 89 c3 48 89 f8 48 c1 e8 03 42 80 3c 28 00 0f 85 5b 08 00 00 48 8d 7b 28 48 8b 55 20 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 dd 08 00 00 48 8d 7d 28 48 8b 43 28 48 89 f9
RSP: 0018:ffffc900033fef30 EFLAGS: 00010206
RAX: 0000000000000005 RBX: 0000000000000000 RCX: ffffffff81fd2b77
RDX: 0000000000000200 RSI: ffffffff81fd2e15 RDI: 0000000000000028
RBP: ffff888074ee20e8 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000fffffffa R11: 0000000000000003 R12: 0000000000000019
R13: dffffc0000000000 R14: ffff88807fb36000 R15: ffffed100ff66c2c
FS:  0000555556c24380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6250121b3b CR3: 000000001f25d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __block_write_begin_int+0x3c0/0x1560 fs/buffer.c:2119
 __block_write_begin fs/buffer.c:2168 [inline]
 block_write_begin+0xb1/0x490 fs/buffer.c:2227
 bfs_write_begin+0x31/0xd0 fs/bfs/file.c:177
 generic_perform_write+0x278/0x600 mm/filemap.c:3918
 __generic_file_write_iter+0x1f9/0x240 mm/filemap.c:4013
 generic_file_write_iter+0xe3/0x350 mm/filemap.c:4039
 __kernel_write_iter+0x261/0x7b0 fs/read_write.c:517
 __kernel_write+0xf6/0x140 fs/read_write.c:537
 __dump_emit fs/coredump.c:813 [inline]
 dump_emit+0x21d/0x330 fs/coredump.c:850
 writenote+0x215/0x2b0 fs/binfmt_elf.c:1422
 write_note_info fs/binfmt_elf.c:1897 [inline]
 elf_core_dump+0x250c/0x3900 fs/binfmt_elf.c:2064
 do_coredump+0x2c97/0x3fd0 fs/coredump.c:764
 get_signal+0x2438/0x2790 kernel/signal.c:2890
 arch_do_signal_or_restart+0x90/0x7f0 arch/x86/kernel/signal.c:309
 exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
 exit_to_user_mode_prepare+0x121/0x240 kernel/entry/common.c:204
 irqentry_exit_to_user_mode+0xa/0x40 kernel/entry/common.c:309
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0033:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 002b:0000000020000008 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 0000000000000020 RCX: 00007f3fa02f7db9
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000555500000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000f4240
R13: 00007ffdb733b1e8 R14: 0000000000000001 R15: 00007ffdb733afb0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bfs_move_block fs/bfs/file.c:42 [inline]
RIP: 0010:bfs_move_blocks fs/bfs/file.c:56 [inline]
RIP: 0010:bfs_get_block+0x3b2/0xeb0 fs/bfs/file.c:125
Code: a8 ff 48 8d 7d 20 48 89 c3 48 89 f8 48 c1 e8 03 42 80 3c 28 00 0f 85 5b 08 00 00 48 8d 7b 28 48 8b 55 20 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 dd 08 00 00 48 8d 7d 28 48 8b 43 28 48 89 f9
RSP: 0018:ffffc900033fef30 EFLAGS: 00010206
RAX: 0000000000000005 RBX: 0000000000000000 RCX: ffffffff81fd2b77
RDX: 0000000000000200 RSI: ffffffff81fd2e15 RDI: 0000000000000028
RBP: ffff888074ee20e8 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000fffffffa R11: 0000000000000003 R12: 0000000000000019
R13: dffffc0000000000 R14: ffff88807fb36000 R15: ffffed100ff66c2c
FS:  0000555556c24380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000001f25d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	a8 ff                	test   $0xff,%al
   2:	48 8d 7d 20          	lea    0x20(%rbp),%rdi
   6:	48 89 c3             	mov    %rax,%rbx
   9:	48 89 f8             	mov    %rdi,%rax
   c:	48 c1 e8 03          	shr    $0x3,%rax
  10:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1)
  15:	0f 85 5b 08 00 00    	jne    0x876
  1b:	48 8d 7b 28          	lea    0x28(%rbx),%rdi
  1f:	48 8b 55 20          	mov    0x20(%rbp),%rdx
  23:	48 89 f8             	mov    %rdi,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
  2f:	0f 85 dd 08 00 00    	jne    0x912
  35:	48 8d 7d 28          	lea    0x28(%rbp),%rdi
  39:	48 8b 43 28          	mov    0x28(%rbx),%rax
  3d:	48 89 f9             	mov    %rdi,%rcx

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/11/21 14:14 upstream 98b1cc82c4af cb976f63 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-gce-selinux-root general protection fault in bfs_get_block
2023/12/14 08:01 upstream 5bd7ef53ffe5 3222d10c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root general protection fault in bfs_get_block
* Struck through repros no longer work on HEAD.