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Sat, 14 Nov 2026 04:09:28 -0800 (PST) Date: Sat, 14 Nov 2026 04:09:28 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6af84f78.097d52ff.3d440.0004.GAE@google.com> Subject: [syzbot] [squashfs?] general protection fault in lookup_open From: syzbot To: brauner@kernel.org, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, phillip@squashfs.org.uk, squashfs-devel@lists.sourceforge.net, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 84abb955b101 Add linux-next specific files for 20261113 git tree: linux-next console+strace: https://syzkaller.appspot.com/x/log.txt?x=1082844d580000 kernel config: https://syzkaller.appspot.com/x/.config?x=d9d5eeb0ba036071 dashboard link: https://syzkaller.appspot.com/bug?extid=0b7a8fb8279a59e8a188 compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=148b45be580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=160f55a1580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/ffae1d4a717e/disk-84abb955.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/fd2a35a63abf/vmlinux-84abb955.xz kernel image: https://storage.googleapis.com/syzbot-assets/039ccf647778/bzImage-84abb955.xz mounted in repro: https://storage.googleapis.com/syzbot-assets/90d273be2ea1/mount_0.gz AI-generated root cause summary: In fs/squashfs/namei.c:squashfs_lookup(), sanity checks using squashfs_dir_space() jump directly to label read_failure instead of data_error upon detecting that a directory entry extends beyond inode size. Jumping to read_failure bypasses the assignment of err = -EIO, leaving err set to either an uninitialized value or a positive value returned by a prior successful call to squashfs_read_metadata() (such as sizeof(struct squashfs_dir_entry) == 8). Consequently, squashfs_lookup() returns ERR_PTR(8), which IS_ERR() does not recognize as an error pointer; VFS lookup_open() subsequently dereferences dentry->d_inode at address 0x8 + 0x68 = 0x70, triggering a near-NULL pointer dereference crash. full analysis: https://syzkaller.appspot.com/x/ai_root_cause?x=0b7a8fb8279a59e8a188 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+0b7a8fb8279a59e8a188@syzkaller.appspotmail.com loop0: detected capacity change from 0 to 8 SQUASHFS error: Unable to read directory block [0:26] Oops: general protection fault, probably for non-canonical address 0xdffffc000000000d: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f] CPU: 1 UID: 0 PID: 5645 Comm: syz-executor126 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026 RIP: 0010:lookup_open+0x890/0x16e0 fs/namei.c:4648 Code: 09 00 00 e8 a2 60 68 ff 49 81 ff 01 f0 ff ff 0f 83 2a ff ff ff 4d 8d 77 68 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 92 54 e8 ff 49 83 3e 00 74 07 e8 67 RSP: 0018:ffffc900039579c0 EFLAGS: 00010203 RAX: 000000000000000d RBX: 0000000000000040 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 00000000ffffffff RBP: 00000000ffffffe2 R08: ffff8880134403fb R09: 1ffff1100268807f R10: dffffc0000000000 R11: ffffed1002688080 R12: 1ffff110026f064c R13: ffffc90003957e00 R14: 000000000000006e R15: 0000000000000006 FS: 0000555559c4d400(0000) GS:ffff8881234cd000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000000b400 CR3: 0000000071a58000 CR4: 00000000003526f0 Call Trace: open_last_lookups fs/namei.c:4880 [inline] path_openat+0x7a5/0x20e0 fs/namei.c:5119 do_file_open+0x23e/0x4a0 fs/namei.c:5151 do_sys_openat2+0x115/0x200 fs/open.c:1492 do_sys_open fs/open.c:1498 [inline] __do_sys_openat fs/open.c:1838 [inline] __se_sys_openat fs/open.c:1833 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1833 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x171/0x540 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x00007fc862573909 Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 0f 1f 44 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 d8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff58fa7d68 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc862573909 RDX: 000000000000275a RSI: 000020000000b400 RDI: 00000000ffffff9c RBP: 0000000000000001 R08: 0000000000000000 R09: 0000555559c4e580 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff58fa7d90 R13: 0000000000000002 R14: 431bde82d7b634db R15: 00007fc8625d304b Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:lookup_open+0x890/0x16e0 fs/namei.c:4648 Code: 09 00 00 e8 a2 60 68 ff 49 81 ff 01 f0 ff ff 0f 83 2a ff ff ff 4d 8d 77 68 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 92 54 e8 ff 49 83 3e 00 74 07 e8 67 RSP: 0018:ffffc900039579c0 EFLAGS: 00010203 RAX: 000000000000000d RBX: 0000000000000040 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 00000000ffffffff RBP: 00000000ffffffe2 R08: ffff8880134403fb R09: 1ffff1100268807f R10: dffffc0000000000 R11: ffffed1002688080 R12: 1ffff110026f064c R13: ffffc90003957e00 R14: 000000000000006e R15: 0000000000000006 FS: 0000555559c4d400(0000) GS:ffff8881233cd000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000557377da1760 CR3: 0000000071a58000 CR4: 00000000003526f0 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 00 00 add %al,(%rax) 2: e8 a2 60 68 ff call 0xff6860a9 7: 49 81 ff 01 f0 ff ff cmp $0xfffffffffffff001,%r15 e: 0f 83 2a ff ff ff jae 0xffffff3e 14: 4d 8d 77 68 lea 0x68(%r15),%r14 18: 4c 89 f0 mov %r14,%rax 1b: 48 c1 e8 03 shr $0x3,%rax 1f: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx 26: fc ff df * 29: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction 2d: 74 08 je 0x37 2f: 4c 89 f7 mov %r14,%rdi 32: e8 92 54 e8 ff call 0xffe854c9 37: 49 83 3e 00 cmpq $0x0,(%r14) 3b: 74 07 je 0x44 3d: e8 .byte 0xe8 3e: 67 addr32 --- 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@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup