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 71c061d2443814de15e177489d5cc00a4a253ef3 testing commit 71c061d2443814de15e177489d5cc00a4a253ef3 with gcc (GCC) 8.1.0 kernel signature: cd93a4bf950d1622a1fbf201cc8418b36b7ba9a0f118fb252c7f8ed29ab6773e all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in hfs_find_init revisions tested: 2, total time: 15m16.274683314s (build: 9m7.406411761s, test: 5m25.011105572s) the crash still happens on HEAD commit msg: Merge tag 'for-5.11-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 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 loop3: detected capacity change from 8192 to 0 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 110914067 P4D 110914067 PUD 110915067 PMD 0 Oops: 0000 [#1] SMP CPU: 0 PID: 3764 Comm: syz-executor3 Not tainted 5.11.0-rc2-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 16 4b e0 ff 48 85 c0 74 23 RSP: 0018:ffffc90000397998 EFLAGS: 00010246 RAX: ffff88810efce800 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffc900003979b8 RDI: 0000000000000000 RBP: ffffc900003979a8 R08: ffffffff84ff2698 R09: 6cfe189d1f56bee0 R10: ffffc90000397a10 R11: 0000000000000286 R12: ffffc900003979b8 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88810e0355e8 FS: 00007f0cbd9c6700(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000040 CR3: 0000000110913000 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+0x119/0x420 fs/buffer.c:2288 hfs_readpage+0x13/0x20 fs/hfs/inode.c:39 do_read_cache_page+0x5db/0x780 mm/filemap.c:3097 read_cache_page+0xd/0x10 mm/filemap.c:3196 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:1366 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:1496 do_new_mount fs/namespace.c:2878 [inline] path_mount+0x765/0xaf0 fs/namespace.c:3208 do_mount+0x77/0x90 fs/namespace.c:3221 __do_sys_mount fs/namespace.c:3429 [inline] __se_sys_mount fs/namespace.c:3406 [inline] __x64_sys_mount+0xc0/0xe0 fs/namespace.c:3406 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:00007f0cbd9c5bb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000020000000 RCX: 0000000000457a7a RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f0cbd9c5c00 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 c06ac782aa9397b5 ]--- 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 16 4b e0 ff 48 85 c0 74 23 RSP: 0018:ffffc90000397998 EFLAGS: 00010246 RAX: ffff88810efce800 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffc900003979b8 RDI: 0000000000000000 RBP: ffffc900003979a8 R08: ffffffff84ff2698 R09: 6cfe189d1f56bee0 R10: ffffc90000397a10 R11: 0000000000000286 R12: ffffc900003979b8 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88810e0355e8 FS: 00007f0cbd9c6700(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000040 CR3: 0000000110913000 CR4: 0000000000350ef0