Re: [syzbot] [raid?] general protection fault in ppl_write_stripe_run

Re: [syzbot] [raid?] general protection fault in ppl_write_stripe_run

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+75d7e96ad03ac2dbbd9f@syzkaller.appspotmail.com
Tested-by: syzbot+75d7e96ad03ac2dbbd9f@syzkaller.appspotmail.com

Tested on:

commit:         50d05c7c Merge tag 'landlock-7.3-rc3' of git://git.ker..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=16edad25580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=85bc5cc2fc7394d9
dashboard link: https://syzkaller.appspot.com/bug?extid=75d7e96ad03ac2dbbd9f
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
userspace arch: i386
patch:          https://syzkaller.appspot.com/x/patch.diff?x=135a9d15580000

Note: testing is done by a robot and is best-effort only.

[syzbot] [raid?] general protection fault in ppl_write_stripe_run

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    50d05c7c76c9 Merge tag 'landlock-7.3-rc3' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17cfb4c9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=85bc5cc2fc7394d9
dashboard link: https://syzkaller.appspot.com/bug?extid=75d7e96ad03ac2dbbd9f
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
userspace arch: i386
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11849405580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-50d05c7c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/303a0ade8f9e/vmlinux-50d05c7c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/70b8ca71442b/bzImage-50d05c7c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+75d7e96ad03ac2dbbd9f@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 1 UID: 0 PID: 6845 Comm: md0_raid5 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:ppl_write_stripe_run+0x60/0x1320 drivers/md/raid5-ppl.c:538
Code: 3c 02 00 0f 85 01 11 00 00 4c 8b 8b 48 09 00 00 49 8d 41 10 48 89 c2 48 89 44 24 60 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e b9 10 00 00 41 8b 59 10 31 ff
RSP: 0018:ffffc900077e7938 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888013c2c000 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff888aae3d RDI: ffff888013c2c948
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888022c26000
R13: dffffc0000000000 R14: ffff888013c2c2b8 R15: ffff888013c2c000
FS:  0000000000000000(0000) GS:ffff888096a60000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000fff8cec0 CR3: 000000006b079000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 log_flush_stripe_to_raid drivers/md/raid5-log.h:101 [inline]
 handle_active_stripes.isra.0+0x11e4/0x1540 drivers/md/raid5.c:6851
 raid5d+0xe00/0x17b0 drivers/md/raid5.c:6985
 md_thread+0x505/0x580 drivers/md/md.c:8706
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ppl_write_stripe_run+0x60/0x1320 drivers/md/raid5-ppl.c:538
Code: 3c 02 00 0f 85 01 11 00 00 4c 8b 8b 48 09 00 00 49 8d 41 10 48 89 c2 48 89 44 24 60 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e b9 10 00 00 41 8b 59 10 31 ff
RSP: 0018:ffffc900077e7938 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888013c2c000 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff888aae3d RDI: ffff888013c2c948
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888022c26000
R13: dffffc0000000000 R14: ffff888013c2c2b8 R15: ffff888013c2c000
FS:  0000000000000000(0000) GS:ffff888096a60000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000fff8cec0 CR3: 000000006b079000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	3c 02                	cmp    $0x2,%al
   2:	00 0f                	add    %cl,(%rdi)
   4:	85 01                	test   %eax,(%rcx)
   6:	11 00                	adc    %eax,(%rax)
   8:	00 4c 8b 8b          	add    %cl,-0x75(%rbx,%rcx,4)
   c:	48 09 00             	or     %rax,(%rax)
   f:	00 49 8d             	add    %cl,-0x73(%rcx)
  12:	41 10 48 89          	adc    %cl,-0x77(%r8)
  16:	c2 48 89             	ret    $0x8948
  19:	44 24 60             	rex.R and $0x60,%al
  1c:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  23:	fc ff df
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	0f b6 04 02          	movzbl (%rdx,%rax,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	74 08                	je     0x3a
  32:	3c 03                	cmp    $0x3,%al
  34:	0f 8e b9 10 00 00    	jle    0x10f3
  3a:	41 8b 59 10          	mov    0x10(%r9),%ebx
  3e:	31 ff                	xor    %edi,%edi


---
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