Good day,
Dear Maintainers, I found the following bug: Kernel branch: 6.3.0-next-20230426 Kernel config: https://drive.google.com/file/d/1KU1ivdc6axWGXqmaODg5wYNJZ4v7p75j/view?usp=sharing C reproducer: https://drive.google.com/file/d/14qxiXna1l9BLxDH2Ozo6oebnhjbNi06e/view?usp=sharing loop4: detected capacity change from 0 to 16 erofs: (device loop4): EXPERIMENTAL compressed fragments feature in use. Use at your own risk! erofs: (device loop4): EXPERIMENTAL global deduplication feature in use. Use at your own risk! general protection fault, probably for non-canonical address 0xdffffc0000000019: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x00000000000000c8-0x00000000000000cf] CPU: 6 PID: 14033 Comm: syz-executor.4 Not tainted 6.3.0-next-20230426 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:erofs_bread+0x56/0x6d0 fs/erofs/data.c:38 Code: 48 c1 ea 03 80 3c 02 00 0f 85 17 06 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 23 49 8d bc 24 ca 00 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 84 05 00 00 RSP: 0018:ffffc90003f9f980 EFLAGS: 00010212 RAX: dffffc0000000000 RBX: ffffc90003f9faf8 RCX: ffffc9001350c000 RDX: 0000000000000019 RSI: ffffffff83b7198f RDI: 00000000000000ca RBP: 0000000000000000 R08: 0000000000000001 R09: 000000000000003f R10: 000000000000000c R11: 000000000008c001 R12: 0000000000000000 R13: 0000000000000001 R14: ffff888079bfa000 R15: ffff888079bfa000 FS: 00007f5338e33700(0000) GS:ffff888119f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5337c61c40 CR3: 0000000045e57000 CR4: 0000000000350ee0 Call Trace: <TASK> erofs_read_metadata+0xbb/0x490 fs/erofs/super.c:137 erofs_xattr_prefixes_init+0x3b1/0x590 fs/erofs/xattr.c:684 erofs_fc_fill_super+0x1732/0x2a70 fs/erofs/super.c:825 get_tree_bdev+0x44a/0x770 fs/super.c:1303 vfs_get_tree+0x8d/0x350 fs/super.c:1510 do_new_mount fs/namespace.c:3039 [inline] path_mount+0x675/0x1e30 fs/namespace.c:3369 do_mount fs/namespace.c:3382 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x283/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f5337c9176e Code: 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 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:00007f5338e32a08 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 00007f5337c9176e RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f5338e32a60 RBP: 00007f5338e32aa0 R08: 00007f5338e32aa0 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000020000000 R13: 0000000020000100 R14: 00007f5338e32a60 R15: 00000000200108a0 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:erofs_bread+0x56/0x6d0 fs/erofs/data.c:38 Code: 48 c1 ea 03 80 3c 02 00 0f 85 17 06 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 23 49 8d bc 24 ca 00 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 84 05 00 00 RSP: 0018:ffffc90003f9f980 EFLAGS: 00010212 RAX: dffffc0000000000 RBX: ffffc90003f9faf8 RCX: ffffc9001350c000 RDX: 0000000000000019 RSI: ffffffff83b7198f RDI: 00000000000000ca RBP: 0000000000000000 R08: 0000000000000001 R09: 000000000000003f R10: 000000000000000c R11: 000000000008c001 R12: 0000000000000000 R13: 0000000000000001 R14: ffff888079bfa000 R15: ffff888079bfa000 FS: 00007f5338e33700(0000) GS:ffff888119f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5337c61c40 CR3: 0000000045e57000 CR4: 0000000000350ee0 ---------------- Code disassembly (best guess): 0: 48 c1 ea 03 shr $0x3,%rdx 4: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) 8: 0f 85 17 06 00 00 jne 0x625 e: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 15: fc ff df 18: 4c 8b 23 mov (%rbx),%r12 1b: 49 8d bc 24 ca 00 00 lea 0xca(%r12),%rdi 22: 00 23: 48 89 fa mov %rdi,%rdx 26: 48 c1 ea 03 shr $0x3,%rdx * 2a: 0f b6 04 02 movzbl (%rdx,%rax,1),%eax <-- trapping instruction 2e: 48 89 fa mov %rdi,%rdx 31: 83 e2 07 and $0x7,%edx 34: 38 d0 cmp %dl,%al 36: 7f 08 jg 0x40 38: 84 c0 test %al,%al 3a: 0f 85 84 05 00 00 jne 0x5c4 Thank you very much! Best Regards, [Block U Logo] Khagan Karimov (He/His/Him) Ph.D. student | Security Researcher Kahlert School of Computing, The University of Utah meritpages.com/khagan_karimov khagan.net
