Dear Linux Developer, Recently when using our tool to fuzz kernel, the following crash was triggered: HEAD commit: 64570fbc14f8 Linux 5.15-rc5 git tree: upstream compiler: gcc 8.0.1 console output: https://drive.google.com/file/d/1XbBDSFuHIAMsOAmvF0ITxNg8CEr443UB/view?usp=share_link kernel config: https://drive.google.com/file/d/1uDOeEYgJDcLiSOrx9W8v2bqZ6uOA_55t/view?usp=share_link Unfortunately, I don't have any reproducer for this crash yet. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: Wei Chen <harperchen1110@xxxxxxxxx> RBP: 000000000000004a R08: 00000000200007c0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119bfac R13: 0000000000000000 R14: 000000000119bfa0 R15: 00007fffa5a71650 BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 14091067 P4D 14091067 PUD 14092067 PMD 0 Oops: 0000 [#1] PREEMPT SMP CPU: 1 PID: 13456 Comm: syz-executor.0 Not tainted 5.15.0-rc5 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014 RIP: 0010:__list_del_entry_valid+0x2d/0x50 Code: 01 00 00 00 00 ad de 48 8b 07 48 8b 57 08 48 39 c8 0f 84 cd cb 46 02 48 b9 22 01 00 00 00 00 ad de 48 39 ca 0f 84 f0 cb 46 02 <48> 8b 32 48 39 fe 0f 85 d0 cb 46 02 48 8b 50 08 48 39 f2 0f 85 b5 RSP: 0018:ffffc9000cf63c28 EFLAGS: 00010217 RAX: 0000000000000000 RBX: ffff88800f2113d8 RCX: dead000000000122 RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88800f211490 RBP: 0000000000000079 R08: 0000000000000000 R09: 0000000000000001 R10: ffffffff86485018 R11: 0000000000000000 R12: 000000000000001f R13: 0000000000000000 R14: ffffffff8518ba40 R15: 0000000000000000 FS: 00007f0e4932c700(0000) GS:ffff88813dc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000014090000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: fscache_free_cookie+0x45/0x120 fscache_alloc_cookie+0x331/0x350 __fscache_acquire_cookie+0x132/0x620 v9fs_cache_session_get_cookie+0x7d/0x140 v9fs_session_init+0x798/0xac0 v9fs_mount+0x53/0x480 legacy_get_tree+0x2e/0x90 vfs_get_tree+0x29/0x100 path_mount+0x58e/0x10a0 do_mount+0x9b/0xb0 __x64_sys_mount+0x13a/0x150 do_syscall_64+0x34/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4692c9 Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f0e4932bc38 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f0e4932bc80 RCX: 00000000004692c9 RDX: 00000000200002c0 RSI: 0000000020000100 RDI: 0000000000000000 RBP: 000000000000004a R08: 00000000200007c0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119bfac R13: 0000000000000000 R14: 000000000119bfa0 R15: 00007fffa5a71650 Modules linked in: CR2: 0000000000000000 ---[ end trace 15cdfd4d79de03b8 ]--- RIP: 0010:__list_del_entry_valid+0x2d/0x50 Code: 01 00 00 00 00 ad de 48 8b 07 48 8b 57 08 48 39 c8 0f 84 cd cb 46 02 48 b9 22 01 00 00 00 00 ad de 48 39 ca 0f 84 f0 cb 46 02 <48> 8b 32 48 39 fe 0f 85 d0 cb 46 02 48 8b 50 08 48 39 f2 0f 85 b5 RSP: 0018:ffffc9000cf63c28 EFLAGS: 00010217 RAX: 0000000000000000 RBX: ffff88800f2113d8 RCX: dead000000000122 RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88800f211490 RBP: 0000000000000079 R08: 0000000000000000 R09: 0000000000000001 R10: ffffffff86485018 R11: 0000000000000000 R12: 000000000000001f R13: 0000000000000000 R14: ffffffff8518ba40 R15: 0000000000000000 FS: 00007f0e4932c700(0000) GS:ffff88813dc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000014090000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 01 00 add %eax,(%rax) 2: 00 00 add %al,(%rax) 4: 00 ad de 48 8b 07 add %ch,0x78b48de(%rbp) a: 48 8b 57 08 mov 0x8(%rdi),%rdx e: 48 39 c8 cmp %rcx,%rax 11: 0f 84 cd cb 46 02 je 0x246cbe4 17: 48 b9 22 01 00 00 00 movabs $0xdead000000000122,%rcx 1e: 00 ad de 21: 48 39 ca cmp %rcx,%rdx 24: 0f 84 f0 cb 46 02 je 0x246cc1a * 2a: 48 8b 32 mov (%rdx),%rsi <-- trapping instruction 2d: 48 39 fe cmp %rdi,%rsi 30: 0f 85 d0 cb 46 02 jne 0x246cc06 36: 48 8b 50 08 mov 0x8(%rax),%rdx 3a: 48 39 f2 cmp %rsi,%rdx 3d: 0f .byte 0xf 3e: 85 .byte 0x85 3f: b5 .byte 0xb5 Best, Wei -- Linux-cachefs mailing list Linux-cachefs@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/linux-cachefs
