bisecting fixing commit since dce0f88600e49746b4bda873965b671a23ff4313 building syzkaller on 9ebcc5b1a8145326065b932958d82ada85a5c224 testing commit dce0f88600e49746b4bda873965b671a23ff4313 with gcc (GCC) 8.1.0 kernel signature: acb47792579ce8b878dbb54cb96ea169a7b6678dfd8a68627f126ed426269059 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: use-after-free 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 get_block run #6: crashed: KASAN: slab-out-of-bounds Read in get_block run #7: crashed: KASAN: slab-out-of-bounds Read in get_block run #8: crashed: KASAN: slab-out-of-bounds Read in get_block run #9: crashed: KASAN: slab-out-of-bounds Read in get_block testing current HEAD c14d30dc9987047b439b03d6e6db7d54d9f7f180 testing commit c14d30dc9987047b439b03d6e6db7d54d9f7f180 with gcc (GCC) 8.1.0 kernel signature: 0e154c580805db542975cf08e58eda5f69af2ccfb748715e0ef0e19e28773944 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 get_block run #6: crashed: KASAN: use-after-free Read in get_block run #7: crashed: KASAN: slab-out-of-bounds Read in get_block run #8: crashed: KASAN: use-after-free Read in get_block run #9: crashed: KASAN: use-after-free Read in get_block revisions tested: 2, total time: 25m42.930592675s (build: 18m20.242930701s, test: 6m14.302790816s) the crash still happens on HEAD commit msg: Linux 4.19.139 crash: KASAN: use-after-free Read in get_block batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 ================================================================== batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! BUG: KASAN: use-after-free in add_chain fs/minix/itree_common.c:14 [inline] BUG: KASAN: use-after-free in get_branch fs/minix/itree_common.c:52 [inline] BUG: KASAN: use-after-free in get_block+0xe25/0x1100 fs/minix/itree_common.c:160 Read of size 2 at addr ffff88808d35018a by task syz-executor.1/7882 CPU: 1 PID: 7882 Comm: syz-executor.1 Not tainted 4.19.139-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x17c/0x22a lib/dump_stack.c:118 print_address_description.cold.6+0x9/0x211 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x307 mm/kasan/report.c:412 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:431 add_chain fs/minix/itree_common.c:14 [inline] get_branch fs/minix/itree_common.c:52 [inline] get_block+0xe25/0x1100 fs/minix/itree_common.c:160 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! V1_minix_get_block+0x9/0x10 fs/minix/itree_v1.c:56 minix_get_block+0xa7/0x110 fs/minix/inode.c:379 __block_write_begin_int+0x392/0x1aa0 fs/buffer.c:1978 __block_write_begin fs/buffer.c:2028 [inline] block_write_begin+0x48/0x260 fs/buffer.c:2087 minix_write_begin+0x2f/0xc0 fs/minix/inode.c:415 generic_perform_write+0x22f/0x480 mm/filemap.c:3162 __generic_file_write_iter+0x201/0x580 mm/filemap.c:3287 generic_file_write_iter+0x302/0x655 mm/filemap.c:3315 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 __kernel_write+0xe4/0x350 fs/read_write.c:506 do_acct_process+0xa6c/0xea0 kernel/acct.c:520 slow_acct_process kernel/acct.c:579 [inline] acct_process+0x39f/0x49e kernel/acct.c:605 do_exit+0x1a9c/0x2db0 kernel/exit.c:877 do_group_exit+0xf8/0x2c0 kernel/exit.c:990 get_signal+0x308/0x1970 kernel/signal.c:2588 do_signal+0x87/0x1860 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x159/0x1e0 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x413/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45cba9 Code: Bad RIP value. RSP: 002b:00007fe3d232ec78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a3 RAX: 0000000000000000 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: 00007fe3d232f6d4 Allocated by task 7875: save_stack mm/kasan/kasan.c:448 [inline] set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:553 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:538 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc+0x12e/0x390 mm/slab.c:3559 getname_flags+0xb8/0x510 fs/namei.c:140 user_path_at_empty+0x1e/0x40 fs/namei.c:2609 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0xbe/0x150 fs/stat.c:185 vfs_lstat include/linux/fs.h:3134 [inline] __do_sys_newlstat fs/stat.c:350 [inline] __se_sys_newlstat+0x85/0xe0 fs/stat.c:344 __x64_sys_newlstat+0x4f/0x70 fs/stat.c:344 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 7875: save_stack mm/kasan/kasan.c:448 [inline] set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x13c/0x220 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kmem_cache_free+0x83/0x290 mm/slab.c:3765 putname+0xa8/0xe0 fs/namei.c:261 filename_lookup.part.21+0x1ec/0x360 fs/namei.c:2358 filename_lookup fs/namei.c:2342 [inline] user_path_at_empty+0x39/0x40 fs/namei.c:2609 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0xbe/0x150 fs/stat.c:185 vfs_lstat include/linux/fs.h:3134 [inline] __do_sys_newlstat fs/stat.c:350 [inline] __se_sys_newlstat+0x85/0xe0 fs/stat.c:344 __x64_sys_newlstat+0x4f/0x70 fs/stat.c:344 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff88808d350100 which belongs to the cache names_cache of size 4096 The buggy address is located 138 bytes inside of 4096-byte region [ffff88808d350100, ffff88808d351100) The buggy address belongs to the page: page:ffffea000234d400 count:1 mapcount:0 mapping:ffff88821bc47800 index:0x0 compound_mapcount: 0 flags: 0xfffe0000008100(slab|head) raw: 00fffe0000008100 ffffea00022d0908 ffffea000234d308 ffff88821bc47800 raw: 0000000000000000 ffff88808d350100 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808d350080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88808d350100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88808d350180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88808d350200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808d350280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================