bisecting fixing commit since 10b84daddbec72c6b440216a69de9a9605127f7a building syzkaller on 0174c6c8f78a3fdd002a73a5fdf559c1b0ec8c34 testing commit 10b84daddbec72c6b440216a69de9a9605127f7a with gcc (GCC) 8.1.0 kernel signature: 677f2c48b5cd944d1f20b82155fbfe921ec25abb7d91b720debb9bd2aac8ff7b all runs: crashed: general protection fault in hfs_find_init testing current HEAD 0477e92881850d44910a7e94fc2c46f96faa131f testing commit 0477e92881850d44910a7e94fc2c46f96faa131f with gcc (GCC) 8.1.0 kernel signature: fba4b92cba65a5eb1f063c1a181bced857a0cd05531438946051c6e79767c9b6 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in hfs_find_init revisions tested: 2, total time: 15m30.33883085s (build: 8m37.57937003s, test: 6m2.346973548s) the crash still happens on HEAD commit msg: Linux 5.10-rc7 crash: BUG: unable to handle kernel NULL pointer dereference in hfs_find_init IPVS: ftp: loaded support on port[0] = 21 IPVS: ftp: loaded support on port[0] = 21 IPVS: ftp: loaded support on port[0] = 21 hfs: unable to locate alternate MDB hfs: continuing without an alternate MDB BUG: kernel NULL pointer dereference, address: 0000000000000040 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 10b2ef067 P4D 10b2ef067 PUD 10b2f0067 PMD 0 Oops: 0000 [#1] SMP CPU: 0 PID: 3680 Comm: syz-executor3 Not tainted 5.10.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:hfs_find_init+0x19/0x60 fs/hfs/bfind.c:21 Code: fe ff ff ff eb 8d cc cc cc cc cc cc cc cc cc cc cc 55 48 89 e5 41 54 49 89 f4 53 48 89 fb 48 89 7e 10 48 c7 46 18 00 00 00 00 <8b> 47 40 be c0 0c 00 00 8d 7c 00 04 e8 56 74 e0 ff 48 85 c0 74 23 RSP: 0018:ffffc9000043b9a0 EFLAGS: 00010246 RAX: ffff88810f7f3000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffc9000043b9c0 RDI: 0000000000000000 RBP: ffffc9000043b9b0 R08: ffffffff84fe0ed8 R09: 96342fd6fa1a0571 R10: ffffc9000043ba18 R11: 0000000000000282 R12: ffffc9000043b9c0 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88810ec17348 FS: 00007fe5907ff700(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000040 CR3: 000000010b2f2000 CR4: 0000000000350ef0 Call Trace: hfs_ext_read_extent+0x53/0x1a0 fs/hfs/extent.c:200 hfs_get_block+0x162/0x220 fs/hfs/extent.c:366 block_read_full_page+0x10b/0x3c0 fs/buffer.c:2288 hfs_readpage+0x13/0x20 fs/hfs/inode.c:39 do_read_cache_page+0x5e1/0x790 mm/filemap.c:3017 read_cache_page+0xd/0x10 mm/filemap.c:3116 read_mapping_page include/linux/pagemap.h:500 [inline] hfs_btree_open+0x136/0x340 fs/hfs/btree.c:78 hfs_mdb_get+0x4ee/0x610 fs/hfs/mdb.c:199 hfs_fill_super+0x361/0x630 fs/hfs/super.c:406 mount_bdev+0x197/0x1d0 fs/super.c:1419 hfs_mount+0x10/0x20 fs/hfs/super.c:456 legacy_get_tree+0x2f/0x50 fs/fs_context.c:592 vfs_get_tree+0x28/0xc0 fs/super.c:1549 do_new_mount fs/namespace.c:2875 [inline] path_mount+0x765/0xaf0 fs/namespace.c:3205 do_mount+0x77/0x90 fs/namespace.c:3218 __do_sys_mount fs/namespace.c:3426 [inline] __se_sys_mount fs/namespace.c:3403 [inline] __x64_sys_mount+0xc0/0xe0 fs/namespace.c:3403 do_syscall_64+0x37/0x80 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x457a7a Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 5d 8f 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 3a 8f fb ff c3 66 0f 1f 84 00 00 00 00 00 RSP: 002b:00007fe5907febb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000020000000 RCX: 0000000000457a7a RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007fe5907fec00 RBP: 0000000000000003 R08: 00000000200001c0 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003 R13: 0000000000000666 R14: 00000000006fba30 R15: 0000000000000000 Modules linked in: CR2: 0000000000000040 ---[ end trace 1c325d92128377f4 ]--- RIP: 0010:hfs_find_init+0x19/0x60 fs/hfs/bfind.c:21 Code: fe ff ff ff eb 8d cc cc cc cc cc cc cc cc cc cc cc 55 48 89 e5 41 54 49 89 f4 53 48 89 fb 48 89 7e 10 48 c7 46 18 00 00 00 00 <8b> 47 40 be c0 0c 00 00 8d 7c 00 04 e8 56 74 e0 ff 48 85 c0 74 23 RSP: 0018:ffffc9000043b9a0 EFLAGS: 00010246 RAX: ffff88810f7f3000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffc9000043b9c0 RDI: 0000000000000000 RBP: ffffc9000043b9b0 R08: ffffffff84fe0ed8 R09: 96342fd6fa1a0571 R10: ffffc9000043ba18 R11: 0000000000000282 R12: ffffc9000043b9c0 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88810ec17348 FS: 00007fe5907ff700(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000040 CR3: 000000010b2f2000 CR4: 0000000000350ef0