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BUG: KASAN: use-after-free in iov_iter_alignment+0x6a1/0x7b0 lib/iov_iter.c:1225
Read of size 4 at addr ffff8880675db054 by task loop0/24634

CPU: 1 PID: 24634 Comm: loop0 Not tainted 5.4.0-syzkaller #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+0x1fb/0x318 lib/dump_stack.c:118
 print_address_description+0x75/0x5c0 mm/kasan/report.c:374
 __kasan_report+0x14b/0x1c0 mm/kasan/report.c:506
 kasan_report+0x26/0x50 mm/kasan/common.c:634
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131
 iov_iter_alignment+0x6a1/0x7b0 lib/iov_iter.c:1225
 iomap_dio_bio_actor+0x1a7/0x11e0 fs/iomap/direct-io.c:203
 iomap_dio_actor+0x2b4/0x4a0 fs/iomap/direct-io.c:375
 iomap_apply+0x370/0x490 fs/iomap/apply.c:80
 iomap_dio_rw+0x8ad/0x1010 fs/iomap/direct-io.c:493
 ext4_dio_read_iter fs/ext4/file.c:77 [inline]
 ext4_file_read_iter+0x834/0xc20 fs/ext4/file.c:128
 lo_rw_aio+0xcbb/0xea0 include/linux/fs.h:1889
 do_req_filebacked drivers/block/loop.c:616 [inline]
 loop_handle_cmd drivers/block/loop.c:1952 [inline]
 loop_queue_work+0x13ab/0x2590 drivers/block/loop.c:1966
 kthread_worker_fn+0x449/0x700 kernel/kthread.c:671
 loop_kthread_worker_fn+0x40/0x60 drivers/block/loop.c:901
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 23727:
 save_stack mm/kasan/common.c:69 [inline]
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc+0x11c/0x1b0 mm/kasan/common.c:510
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
 __do_kmalloc mm/slab.c:3655 [inline]
 __kmalloc+0x254/0x340 mm/slab.c:3664
 kmalloc include/linux/slab.h:561 [inline]
 sk_prot_alloc+0xb0/0x290 net/core/sock.c:1603
 sk_alloc+0x38/0x9c0 net/core/sock.c:1657
 __netlink_create+0x6e/0x200 net/netlink/af_netlink.c:629
 netlink_create+0x39a/0x4f0 net/netlink/af_netlink.c:692
 __sock_create+0x5cc/0x910 net/socket.c:1419
 sock_create net/socket.c:1470 [inline]
 __sys_socket+0xe7/0x2e0 net/socket.c:1512
 __do_sys_socket net/socket.c:1521 [inline]
 __se_sys_socket net/socket.c:1519 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1519
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 16:
 save_stack mm/kasan/common.c:69 [inline]
 set_track mm/kasan/common.c:77 [inline]
 kasan_set_free_info mm/kasan/common.c:332 [inline]
 __kasan_slab_free+0x12a/0x1e0 mm/kasan/common.c:471
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
 __cache_free mm/slab.c:3425 [inline]
 kfree+0x115/0x200 mm/slab.c:3756
 sk_prot_free net/core/sock.c:1640 [inline]
 __sk_destruct+0x623/0x750 net/core/sock.c:1724
 sk_destruct net/core/sock.c:1739 [inline]
 __sk_free+0x35d/0x430 net/core/sock.c:1750
 sk_free+0x51/0x90 net/core/sock.c:1761
 deferred_put_nlk_sk+0x20a/0x250 net/netlink/af_netlink.c:729
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2183 [inline]
 rcu_core+0x833/0x10a0 kernel/rcu/tree.c:2408
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2417
 __do_softirq+0x333/0x7c4 arch/x86/include/asm/paravirt.h:762

The buggy address belongs to the object at ffff8880675db000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 84 bytes inside of
 2048-byte region [ffff8880675db000, ffff8880675db800)
The buggy address belongs to the page:
page:ffffea00019d76c0 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0
raw: 00fffe0000000200 ffffea000157a448 ffffea00012bb908 ffff8880aa400e00
raw: 0000000000000000 ffff8880675db000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880675daf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880675daf80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff8880675db000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff8880675db080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880675db100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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