bisecting fixing commit since b850307b279cbd12ab8c654d1a3dfe55319cc475 building syzkaller on 115e19300f73966554f176e2440fe79572a37c99 testing commit b850307b279cbd12ab8c654d1a3dfe55319cc475 with gcc (GCC) 8.1.0 kernel signature: da5df238a6e460aa4459b4250bb296dc23b49f049f4d3adb78221c7d0807985b run #0: crashed: KASAN: use-after-free Read in get_block run #1: crashed: KASAN: use-after-free Read in get_block run #2: crashed: KASAN: slab-out-of-bounds Read in get_block run #3: crashed: KASAN: use-after-free Read in get_block run #4: crashed: KASAN: use-after-free Read in get_block run #5: crashed: KASAN: slab-out-of-bounds Read in V1_minix_truncate run #6: crashed: KASAN: slab-out-of-bounds Read in get_block run #7: crashed: KASAN: use-after-free Read in get_block run #8: crashed: KASAN: use-after-free Read in get_block run #9: crashed: KASAN: slab-out-of-bounds Read in get_block testing current HEAD 14b58326976de6ef3998eefec1dd7f8b38b97a75 testing commit 14b58326976de6ef3998eefec1dd7f8b38b97a75 with gcc (GCC) 8.1.0 kernel signature: fd4c7a15bf172b5583080c06c1dbadc999001bda63250897c6ea01c3123b5e1e run #0: crashed: KASAN: use-after-free Read in get_block run #1: crashed: KASAN: slab-out-of-bounds Read in get_block run #2: crashed: KASAN: use-after-free Read in get_block run #3: crashed: KASAN: slab-out-of-bounds Read in get_block run #4: crashed: KASAN: use-after-free Read in get_block run #5: crashed: KASAN: use-after-free Read in get_block run #6: crashed: KASAN: use-after-free Read in get_block run #7: crashed: KASAN: use-after-free Read in get_block run #8: crashed: KASAN: use-after-free Read in get_block run #9: crashed: KASAN: slab-out-of-bounds Read in get_block revisions tested: 2, total time: 25m4.766254964s (build: 17m53.262110302s, test: 5m59.34440321s) the crash still happens on HEAD commit msg: Linux 4.14.193 crash: KASAN: slab-out-of-bounds Read in get_block device veth0_macvtap entered promiscuous mode Process accounting resumed IPv6: ADDRCONF(NETDEV_UP): macvtap0: link is not ready audit: type=1800 audit(1597179504.385:12): pid=7766 uid=0 auid=0 ses=8 subj=system_u:system_r:kernel_t:s0 op="collect_data" cause="failed(directio)" comm="syz-executor.2" name="file0" dev="sda1" ino=15754 res=0 ================================================================== BUG: KASAN: slab-out-of-bounds in add_chain fs/minix/itree_common.c:14 [inline] BUG: KASAN: slab-out-of-bounds in get_branch fs/minix/itree_common.c:52 [inline] BUG: KASAN: slab-out-of-bounds in get_block+0xd96/0x1040 fs/minix/itree_common.c:160 Read of size 2 at addr ffff8880a52b218a by task syz-executor.0/7765 CPU: 0 PID: 7765 Comm: syz-executor.0 Not tainted 4.14.193-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 MINIX-fs: mounting unchecked file system, running fsck is recommended Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x14b/0x1f1 lib/dump_stack.c:58 print_address_description.cold.6+0x9/0x1ca mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report.cold.7+0x11a/0x2d4 mm/kasan/report.c:409 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:428 add_chain fs/minix/itree_common.c:14 [inline] get_branch fs/minix/itree_common.c:52 [inline] get_block+0xd96/0x1040 fs/minix/itree_common.c:160 V1_minix_get_block+0x9/0x10 fs/minix/itree_v1.c:56 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 minix_get_block+0xa7/0x110 fs/minix/inode.c:379 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! __block_write_begin_int+0x327/0x1640 fs/buffer.c:2038 __block_write_begin fs/buffer.c:2088 [inline] block_write_begin+0x48/0x240 fs/buffer.c:2147 minix_write_begin+0x2f/0xc0 fs/minix/inode.c:415 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 generic_perform_write+0x227/0x450 mm/filemap.c:3047 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! __generic_file_write_iter+0x201/0x580 mm/filemap.c:3172 generic_file_write_iter+0x302/0x660 mm/filemap.c:3200 IPv6: ADDRCONF(NETDEV_UP): batadv_slave_0: link is not ready call_write_iter include/linux/fs.h:1778 [inline] new_sync_write fs/read_write.c:469 [inline] __vfs_write+0x413/0x840 fs/read_write.c:482 batman_adv: batadv0: Interface activated: batadv_slave_0 __kernel_write+0xe4/0x360 fs/read_write.c:501 do_acct_process+0xa4a/0xe80 kernel/acct.c:520 acct_pin_kill+0x27/0xe0 kernel/acct.c:174 pin_kill+0x134/0x600 fs/fs_pin.c:50 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1 acct_on kernel/acct.c:254 [inline] SYSC_acct kernel/acct.c:286 [inline] SyS_acct+0x519/0x7b0 kernel/acct.c:273 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45cba9 RSP: 002b:00007f9b50219c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a3 RAX: ffffffffffffffda RBX: 00000000004da400 RCX: 000000000045cba9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000480 RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000001c R14: 00000000004c2f71 R15: 00007f9b5021a6d4 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1 Allocated by task 3637: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:551 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:536 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 kmem_cache_alloc+0x12e/0x3e0 mm/slab.c:3552 getname_flags+0xb8/0x510 fs/namei.c:138 user_path_at_empty+0x1e/0x40 fs/namei.c:2631 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0xb6/0x130 fs/stat.c:185 vfs_lstat include/linux/fs.h:3066 [inline] SYSC_newlstat fs/stat.c:350 [inline] SyS_newlstat+0x7d/0xc0 fs/stat.c:344 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! Freed by task 3637: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0xab/0x190 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kmem_cache_free+0x80/0x2d0 mm/slab.c:3758 putname+0xa8/0xe0 fs/namei.c:259 filename_lookup.part.19+0x22c/0x340 fs/namei.c:2386 filename_lookup fs/namei.c:2370 [inline] user_path_at_empty+0x39/0x40 fs/namei.c:2631 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0xb6/0x130 fs/stat.c:185 vfs_lstat include/linux/fs.h:3066 [inline] SYSC_newlstat fs/stat.c:350 [inline] SyS_newlstat+0x7d/0xc0 fs/stat.c:344 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready entry_SYSCALL_64_after_hwframe+0x46/0xbb The buggy address belongs to the object at ffff8880a52b21c0 which belongs to the cache names_cache of size 4096 The buggy address is located 54 bytes to the left of 4096-byte region [ffff8880a52b21c0, ffff8880a52b31c0) The buggy address belongs to the page: page:ffffea000294ac80 count:1 mapcount:0 mapping:ffff8880a52b21c0 index:0x0 compound_mapcount: 0 flags: 0xfffe0000008100(slab|head) raw: 00fffe0000008100 ffff8880a52b21c0 0000000000000000 0000000100000001 batman_adv: batadv0: Interface activated: batadv_slave_1 raw: ffffea000216e420 ffffea00029308a0 ffff8880aa9e1cc0 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a52b2080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880a52b2100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880a52b2180: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff8880a52b2200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a52b2280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================