==================================================================
BUG: KASAN: use-after-free in memset include/linux/string.h:333 [inline]
BUG: KASAN: use-after-free in __ext4_expand_extra_isize+0x175/0x250 fs/ext4/inode.c:5907
Write of size 50776 at addr ffff8880921770a0 by task syz-executor.4/13699

CPU: 1 PID: 13699 Comm: syz-executor.4 Not tainted 4.19.76 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report mm/kasan/report.c:412 [inline]
 kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x123/0x190 mm/kasan/kasan.c:267
 memset+0x24/0x40 mm/kasan/kasan.c:285
 memset include/linux/string.h:333 [inline]
 __ext4_expand_extra_isize+0x175/0x250 fs/ext4/inode.c:5907
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5959 [inline]
 ext4_mark_inode_dirty+0x6f0/0x940 fs/ext4/inode.c:6035
 __ext4_ext_dirty+0x12d/0x170 fs/ext4/extents.c:165
 ext4_ext_remove_space+0x2a27/0x40c0 fs/ext4/extents.c:3069
 ext4_ext_truncate+0x1b5/0x200 fs/ext4/extents.c:4661
 ext4_truncate+0xdf9/0x13d0 fs/ext4/inode.c:4514
 ext4_setattr+0x1b69/0x2520 fs/ext4/inode.c:5649
 notify_change+0xad7/0xfb0 fs/attr.c:334
 do_truncate+0x158/0x220 fs/open.c:63
 handle_truncate fs/namei.c:3008 [inline]
 do_last fs/namei.c:3424 [inline]
 path_openat+0x2c27/0x45e0 fs/namei.c:3534
 do_filp_open+0x1a1/0x280 fs/namei.c:3564
 do_sys_open+0x3fe/0x550 fs/open.c:1088
 ksys_open include/linux/syscalls.h:1276 [inline]
 __do_sys_creat fs/open.c:1146 [inline]
 __se_sys_creat fs/open.c:1144 [inline]
 __x64_sys_creat+0x61/0x80 fs/open.c:1144
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459a29
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f78ba733c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
audit: type=1804 audit(1570061093.937:411): pid=13692 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op=invalid_pcr cause=open_writers comm="syz-executor.1" name="/root/syzkaller-testdir437884791/syzkaller.goh6Qp/660/bus" dev="sda1" ino=17361 res=1
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 0000000000459a29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020001c00
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f78ba7346d4
R13: 00000000004c0090 R14: 00000000004d23b0 R15: 00000000ffffffff

The buggy address belongs to the page:
page:ffffea0002485dc0 count:2 mapcount:0 mapping:ffff8882194e6a98 index:0x458
flags: 0x1fffc0000001074(referenced|dirty|lru|active|private)
raw: 01fffc0000001074 ffffea0001d93f88 ffffea0001cb5208 ffff8882194e6a98
raw: 0000000000000458 ffff888042d60f18 00000002ffffffff ffff888098a08240
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff888098a08240

Memory state around the buggy address:
 ffff888092177f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888092177f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888092178000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888092178080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888092178100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
audit: type=1804 audit(1570061093.937:412): pid=13692 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op=invalid_pcr cause=open_writers comm="syz-executor.1" name="/root/syzkaller-testdir437884791/syzkaller.goh6Qp/660/bus" dev="sda1" ino=17361 res=1
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 1 PID: 13704 Comm: syz-executor.0 Tainted: G    B             4.19.76 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold+0xa/0x1b lib/fault-inject.c:149
 __should_failslab+0x121/0x190 mm/failslab.c:32
 should_failslab+0x9/0x14 mm/slab_common.c:1557
 slab_pre_alloc_hook mm/slab.h:424 [inline]
 slab_alloc mm/slab.c:3383 [inline]
 __do_kmalloc mm/slab.c:3725 [inline]
 __kmalloc+0x2e2/0x750 mm/slab.c:3736
 kmalloc_array include/linux/slab.h:637 [inline]
 kcalloc include/linux/slab.h:648 [inline]
 ext4_find_extent+0x76e/0x9d0 fs/ext4/extents.c:892
 ext4_ext_map_blocks+0x1c3/0x55c0 fs/ext4/extents.c:4303
 ext4_da_map_blocks fs/ext4/inode.c:1865 [inline]
 ext4_da_get_block_prep+0xd21/0x15f0 fs/ext4/inode.c:1956
 __block_write_begin_int+0x4dd/0x1910 fs/buffer.c:1967
 __block_write_begin+0x31/0x40 fs/buffer.c:2017
 ext4_da_write_begin+0x511/0xec0 fs/ext4/inode.c:3092
 generic_perform_write+0x22a/0x520 mm/filemap.c:3161
 __generic_file_write_iter+0x25e/0x630 mm/filemap.c:3286
 ext4_file_write_iter+0x32b/0x1060 fs/ext4/file.c:270
 call_write_iter include/linux/fs.h:1820 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x587/0x810 fs/read_write.c:487
 vfs_write+0x20c/0x560 fs/read_write.c:549
 ksys_write+0x14f/0x2d0 fs/read_write.c:599
 __do_sys_write fs/read_write.c:611 [inline]
 __se_sys_write fs/read_write.c:608 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:608
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459a29
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f398b07cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f398b07cc90 RCX: 0000000000459a29
RDX: 00000000000297ef RSI: 0000000020000080 RDI: 0000000000000006
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f398b07d6d4
R13: 00000000004c9e0f R14: 00000000004e1a10 R15: 0000000000000007
audit: type=1804 audit(1570061094.077:413): pid=13702 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op=invalid_pcr cause=open_writers comm="syz-executor.1" name="/root/syzkaller-testdir437884791/syzkaller.goh6Qp/660/bus" dev="sda1" ino=17361 res=1