I report a null pointer dereference bug (in linux-5.9.0-rc6) found by kernel fuzz. kernel config: https://github.com/butterflyhack/syzkaller-fuzz/blob/master/v5.9.0-rc6-config and can reproduce. the crash log is asblow: RBP: 0000000020000000 R08: 00007f5988f22b00 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000100 R13: 0000000020000200 R14: 00007f5988f22ac0 R15: 0000000020013b00 general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 0 PID: 11738 Comm: syz-executor.3 Not tainted 5.9.0-rc6+ #15 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 RIP: 0010:__list_del_entry_valid+0x1d/0xef lib/list_debug.c:42 Code: 48 8b 34 24 eb b4 0f 1f 80 00 00 00 00 48 b8 00 00 00 00 00 fc ff df 41 55 41 54 55 48 89 fd 48 83 c7 08 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 a0 00 00 00 48 89 ea 4c 8b 65 08 48 b8 00 00 00 RSP: 0018:ffffc90004137a98 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: dffffc0000000000 RCX: ffffc90007b41000 RDX: 0000000000000001 RSI: ffffffff82245325 RDI: 0000000000000008 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000003 R10: fffff52000826f49 R11: 0000000000000001 R12: ffffed1004cde473 R13: ffff8880266f2498 R14: 0000000000000008 R15: 0000000000000000 FS: 00007f5988f23700(0000) GS:ffff88806c000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000768000 CR3: 0000000069d71003 CR4: 0000000000370ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 000000000000886c DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: __list_del_entry include/linux/list.h:132 [inline] list_del_init include/linux/list.h:204 [inline] __exfat_cache_inval_inode fs/exfat/cache.c:212 [inline] exfat_cache_inval_inode+0xb3/0x310 fs/exfat/cache.c:227 exfat_evict_inode+0x76/0x33e fs/exfat/inode.c:660 evict+0x2ed/0x750 fs/inode.c:576 iput_final fs/inode.c:1652 [inline] iput.part.0+0x424/0x850 fs/inode.c:1678 iput+0x58/0x70 fs/inode.c:1668 exfat_fill_super.cold+0x32/0x65a fs/exfat/super.c:681 get_tree_bdev+0x421/0x740 fs/super.c:1342 vfs_get_tree+0x89/0x2f0 fs/super.c:1547 do_new_mount fs/namespace.c:2875 [inline] path_mount+0x1387/0x20a0 fs/namespace.c:3192 do_mount fs/namespace.c:3205 [inline] __do_sys_mount fs/namespace.c:3413 [inline] __se_sys_mount fs/namespace.c:3390 [inline] __x64_sys_mount+0x27f/0x300 fs/namespace.c:3390 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x46acda Code: 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 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:00007f5988f22a68 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f5988f22b00 RCX: 000000000046acda RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f5988f22ac0 RBP: 0000000020000000 R08: 00007f5988f22b00 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000100 R13: 0000000020000200 R14: 00007f5988f22ac0 R15: 0000000020013b00 Modules linked in: Dumping ftrace buffer: (ftrace buffer empty) ---[ end trace 4c5231563b9b92e6 ]--- RIP: 0010:__list_del_entry_valid+0x1d/0xef lib/list_debug.c:42 Code: 48 8b 34 24 eb b4 0f 1f 80 00 00 00 00 48 b8 00 00 00 00 00 fc ff df 41 55 41 54 55 48 89 fd 48 83 c7 08 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 a0 00 00 00 48 89 ea 4c 8b 65 08 48 b8 00 00 00 RSP: 0018:ffffc90004137a98 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: dffffc0000000000 RCX: ffffc90007b41000 RDX: 0000000000000001 RSI: ffffffff82245325 RDI: 0000000000000008 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000003 R10: fffff52000826f49 R11: 0000000000000001 R12: ffffed1004cde473 R13: ffff8880266f2498 R14: 0000000000000008 R15: 0000000000000000 FS: 00007f5988f23700(0000) GS:ffff88806c000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000768000 CR3: 0000000069d71003 CR4: 0000000000370ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 000000000000886c DR6: 00000000ffff0ff0 DR7: 0000000000000400 Regard, butt3rflyh4ck
