general protection fault in open_xa_dir

[syzbot <syzbot+9b33c9b118d77ff59b6f@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    ccc1d052 Merge tag 'dmaengine-fix-5.9' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=143df175900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=adebb40048274f92
dashboard link: https://syzkaller.appspot.com/bug?extid=9b33c9b118d77ff59b6f
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=107b026b900000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=107f17e3900000

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1392c575900000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1052c575900000
console output: https://syzkaller.appspot.com/x/log.txt?x=1792c575900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9b33c9b118d77ff59b6f@syzkaller.appspotmail.com

REISERFS (device loop0): journal params: device loop0, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30
REISERFS (device loop0): checking transaction log (loop0)
REISERFS (device loop0): Using tea hash to sort names
general protection fault, probably for non-canonical address 0xdffffc000000000d: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
CPU: 1 PID: 6851 Comm: syz-executor705 Not tainted 5.9.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:d_really_is_negative include/linux/dcache.h:472 [inline]
RIP: 0010:open_xa_root fs/reiserfs/xattr.c:124 [inline]
RIP: 0010:open_xa_dir+0xad/0x5d0 fs/reiserfs/xattr.c:152
Code: c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 0b 77 b9 ff 4c 8b 2b 49 83 c5 68 4d 89 ee 49 c1 ee 03 48 b8 00 00 00 00 00 fc ff df <41> 80 3c 06 00 74 08 4c 89 ef e8 e4 76 b9 ff 49 8b 7d 00 48 85 ff
RSP: 0018:ffffc90000e97870 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff8880a6e11598 RCX: ffff8880a74bc080
RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffff8880852b37e0
RBP: ffffc90000e978e8 R08: ffffffff81fb5e96 R09: ffffffff81fbc746
R10: 0000000000000002 R11: ffff8880a74bc080 R12: 1ffff11014d9e4cd
R13: 0000000000000068 R14: 000000000000000d R15: ffff8880a6cf2668
FS:  00000000020a1880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000043f290 CR3: 0000000096b7f000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 xattr_lookup+0x24/0x280 fs/reiserfs/xattr.c:395
 reiserfs_xattr_get+0x89/0x540 fs/reiserfs/xattr.c:677
 reiserfs_get_acl+0x63/0x690 fs/reiserfs/xattr_acl.c:209
 get_acl+0x152/0x2e0 fs/posix_acl.c:141
 check_acl fs/namei.c:277 [inline]
 acl_permission_check fs/namei.c:309 [inline]
 generic_permission+0x2ba/0x550 fs/namei.c:353
 do_inode_permission fs/namei.c:398 [inline]
 inode_permission+0x234/0x4a0 fs/namei.c:463
 lookup_one_len+0xa6/0x200 fs/namei.c:2557
 reiserfs_lookup_privroot+0x85/0x1e0 fs/reiserfs/xattr.c:972
 reiserfs_fill_super+0x2b51/0x3240 fs/reiserfs/super.c:2176
 mount_bdev+0x24f/0x360 fs/super.c:1417
 legacy_get_tree+0xea/0x180 fs/fs_context.c:592
 vfs_get_tree+0x88/0x270 fs/super.c:1547
 do_new_mount fs/namespace.c:2875 [inline]
 path_mount+0x179d/0x29e0 fs/namespace.c:3192
 do_mount fs/namespace.c:3205 [inline]
 __do_sys_mount fs/namespace.c:3413 [inline]
 __se_sys_mount+0x126/0x180 fs/namespace.c:3390
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x447dba
Code: b8 08 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 7d a3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 5a a3 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007ffdc5bb7dd8 EFLAGS: 00000297 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffdc5bb7e30 RCX: 0000000000447dba
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffdc5bb7df0
RBP: 00007ffdc5bb7df0 R08: 00007ffdc5bb7e30 R09: 0000000000000000
R10: 0000000000010000 R11: 0000000000000297 R12: 0000000000000007
R13: 0000000000000004 R14: 0000000000000003 R15: 0000000000000003
Modules linked in:
---[ end trace 5bf17987eca6218c ]---
RIP: 0010:d_really_is_negative include/linux/dcache.h:472 [inline]
RIP: 0010:open_xa_root fs/reiserfs/xattr.c:124 [inline]
RIP: 0010:open_xa_dir+0xad/0x5d0 fs/reiserfs/xattr.c:152
Code: c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 0b 77 b9 ff 4c 8b 2b 49 83 c5 68 4d 89 ee 49 c1 ee 03 48 b8 00 00 00 00 00 fc ff df <41> 80 3c 06 00 74 08 4c 89 ef e8 e4 76 b9 ff 49 8b 7d 00 48 85 ff
RSP: 0018:ffffc90000e97870 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff8880a6e11598 RCX: ffff8880a74bc080
RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffff8880852b37e0
RBP: ffffc90000e978e8 R08: ffffffff81fb5e96 R09: ffffffff81fbc746
R10: 0000000000000002 R11: ffff8880a74bc080 R12: 1ffff11014d9e4cd
R13: 0000000000000068 R14: 000000000000000d R15: ffff8880a6cf2668
FS:  00000000020a1880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8a9403b188 CR3: 0000000096b7f000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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