bisecting fixing commit since b850307b279cbd12ab8c654d1a3dfe55319cc475
building syzkaller on eabcced43245881efa7769d938bcaf795ed48742
testing commit b850307b279cbd12ab8c654d1a3dfe55319cc475 with gcc (GCC) 8.4.1 20210217
kernel signature: cde07a798320a1f6ec62b99cf757cb46b7ccf881139bdb784c6392c1c5a344f4
run #0: crashed: KASAN: use-after-free Read in __ext4_check_dir_entry
run #1: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #2: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #3: crashed: KASAN: use-after-free Read in __ext4_check_dir_entry
run #4: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #5: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #6: crashed: KASAN: use-after-free Read in __ext4_check_dir_entry
run #7: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #8: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #9: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #10: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #11: crashed: KASAN: use-after-free Read in __ext4_check_dir_entry
run #12: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #13: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #14: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #15: crashed: KASAN: use-after-free Read in __ext4_check_dir_entry
run #16: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #17: OK
run #18: OK
run #19: crashed: KASAN: use-after-free Read in __ext4_check_dir_entry
testing current HEAD 670d6552eda8ff0c5f396d3d6f0174237917c66c
testing commit 670d6552eda8ff0c5f396d3d6f0174237917c66c with gcc (GCC) 8.4.1 20210217
kernel signature: 00443300cf5e440366c26af2ca1621f68666c76b3e619475dbe24f82094b1022
run #0: crashed: KASAN: out-of-bounds Read in __ext4_check_dir_entry
run #1: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #2: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #3: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #4: crashed: KASAN: use-after-free Read in __ext4_check_dir_entry
run #5: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #6: crashed: KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
run #7: crashed: KASAN: use-after-free Read in __ext4_check_dir_entry
run #8: crashed: KASAN: use-after-free Read in __ext4_check_dir_entry
run #9: OK
revisions tested: 2, total time: 32m45.534091239s (build: 14m45.864635128s, test: 17m32.347350939s)
the crash still happens on HEAD
commit msg: Linux 4.14.227
crash: KASAN: use-after-free Read in __ext4_check_dir_entry
batman_adv: batadv0: Interface activated: batadv_slave_1
device veth1_macvtap entered promiscuous mode
IPv6: ADDRCONF(NETDEV_UP): macsec0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): macvtap0: link becomes ready
==================================================================
BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x2c6/0x3f0 fs/ext4/dir.c:82
Read of size 1 at addr ffff8881daf95001 by task syz-executor.0/7066

CPU: 0 PID: 7066 Comm: syz-executor.0 Not tainted 4.14.227-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x14b/0x1e7 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 mm/kasan/report.c:409 [inline]
 kasan_report.cold.7+0x11a/0x2d3 mm/kasan/report.c:393
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:427
 __ext4_check_dir_entry+0x2c6/0x3f0 fs/ext4/dir.c:82
 ext4_readdir+0x72a/0x3010 fs/ext4/dir.c:240
 iterate_dir+0x188/0x660 fs/readdir.c:52
 SYSC_getdents fs/readdir.c:269 [inline]
 SyS_getdents+0x111/0x1d0 fs/readdir.c:250
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x464599
RSP: 002b:00007f542c24d198 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000464599
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00000000004f5b60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00
R13: 00007f542c24d6bc R14: 00000000ffffffff R15: 0000000000000003

The buggy address belongs to the page:
page:ffffea00076be540 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x17ffe0000000000()
raw: 017ffe0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: ffff8881f672ee98 ffffea0007400c60 ffff8881db217aa8 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881daf94f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881daf94f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881daf95000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8881daf95080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881daf95100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.0: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.0: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
IPv6: ADDRCONF(NETDEV_CHANGE): macsec0: link becomes ready
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.0: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.0: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_vlan: link becomes ready
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.0: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_vlan: link becomes ready
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.0: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.0: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): veth1_vlan: link is not ready
device veth0_vlan entered promiscuous mode
IPv6: ADDRCONF(NETDEV_CHANGE): vlan0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): vlan1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_vlan: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_vlan: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): vlan0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): vlan1: link becomes ready
device veth0_vlan entered promiscuous mode
IPv6: ADDRCONF(NETDEV_UP): veth0_to_batadv: link is not ready
device veth1_vlan entered promiscuous mode
device veth1_vlan entered promiscuous mode
IPv6: ADDRCONF(NETDEV_UP): veth1_to_batadv: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth0_macvtap: link is not ready
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!
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!
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!
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_0: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_0
IPv6: ADDRCONF(NETDEV_UP): veth1_macvtap: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_macvtap: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_macvtap: link becomes ready
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
device veth0_macvtap entered promiscuous mode
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.1: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
IPv6: ADDRCONF(NETDEV_UP): macvtap0: link is not ready
device veth1_macvtap entered promiscuous mode
IPv6: ADDRCONF(NETDEV_UP): macsec0: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth0_macvtap: link is not ready
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.1: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
IPv6: ADDRCONF(NETDEV_UP): veth1_macvtap: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth0_to_batadv: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): macvtap0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): macsec0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_macvtap: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_macvtap: link becomes ready
device veth0_macvtap entered promiscuous mode
IPv6: ADDRCONF(NETDEV_UP): macvtap0: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth1_to_batadv: link is not ready
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!
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!
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!
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!
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_0: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_0
device veth1_macvtap entered promiscuous mode
IPv6: ADDRCONF(NETDEV_UP): macsec0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): macvtap0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): macsec0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_UP): veth0_to_batadv: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.3: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): veth1_to_batadv: link is not ready
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!
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!
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!
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!
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!
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_0: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_0
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
EXT4-fs error: 332 callbacks suppressed
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.4: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.3: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.0: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.1: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.2: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.5: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.3: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.4: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.2: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096
EXT4-fs error (device sda1): ext4_readdir:242: inode #11: block 8230: comm syz-executor.0: path /lost+found: bad entry in directory: rec_len % 4 != 0 - offset=4091, inode=2223847902, rec_len=201, name_len=0, size=4096