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BUG: KASAN: use-after-free in io_uring_show_cred+0x5bb/0x5f0 fs/io_uring.c:9219
Read of size 8 at addr ffff8880205f08a0 by task syz-executor.3/20211

CPU: 1 PID: 20211 Comm: syz-executor.3 Not tainted 5.10.0-rc2-next-20201104-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+0x107/0x163 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385
 __kasan_report mm/kasan/report.c:545 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
 io_uring_show_cred+0x5bb/0x5f0 fs/io_uring.c:9219
 idr_for_each+0x113/0x220 lib/idr.c:208
 __io_uring_show_fdinfo fs/io_uring.c:9272 [inline]
 io_uring_show_fdinfo+0x923/0xda0 fs/io_uring.c:9294
 seq_show+0x4a8/0x700 fs/proc/fd.c:65
 seq_read+0x432/0x1070 fs/seq_file.c:208
 do_loop_readv_writev fs/read_write.c:761 [inline]
 do_loop_readv_writev fs/read_write.c:748 [inline]
 do_iter_read+0x48e/0x6e0 fs/read_write.c:803
 vfs_readv+0xe5/0x150 fs/read_write.c:921
 do_preadv fs/read_write.c:1013 [inline]
 __do_sys_preadv fs/read_write.c:1063 [inline]
 __se_sys_preadv fs/read_write.c:1058 [inline]
 __x64_sys_preadv+0x231/0x310 fs/read_write.c:1058
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45deb9
Code: 0d b4 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 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f04e587ec78 EFLAGS: 00000246
 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 0000000000025e40 RCX: 000000000045deb9
RDX: 0000000000000333 RSI: 00000000200017c0 RDI: 0000000000000007
RBP: 000000000118bf70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c
R13: 00007ffec0e674cf R14: 00007f04e587f9c0 R15: 000000000118bf2c

Allocated by task 8489:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:461
 kmalloc_array+0x42/0x70 include/linux/slab.h:592
 kcalloc include/linux/slab.h:603 [inline]
 ext4_find_extent+0x984/0xce0 fs/ext4/extents.c:863
 ext4_ext_map_blocks+0x1e2/0x5f30 fs/ext4/extents.c:4056
 ext4_map_blocks+0x64f/0x1770 fs/ext4/inode.c:626
 ext4_getblk+0x13c/0x680 fs/ext4/inode.c:836
 ext4_bread+0x29/0x210 fs/ext4/inode.c:888
 ext4_append+0x15d/0x370 fs/ext4/namei.c:67
 ext4_init_new_dir+0x25e/0x4d0 fs/ext4/namei.c:2769
 ext4_mkdir+0x3c8/0xa30 fs/ext4/namei.c:2814
 vfs_mkdir+0x507/0x770 fs/namei.c:3650
 do_mkdirat+0x262/0x2d0 fs/namei.c:3673
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 8489:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
 __kasan_slab_free+0x102/0x140 mm/kasan/common.c:422
 slab_free_hook mm/slub.c:1544 [inline]
 slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1577
 slab_free mm/slub.c:3140 [inline]
 kfree+0xdb/0x360 mm/slub.c:4122
 ext4_ext_map_blocks+0xa15/0x5f30 fs/ext4/extents.c:4335
 ext4_map_blocks+0x64f/0x1770 fs/ext4/inode.c:626
 ext4_getblk+0x13c/0x680 fs/ext4/inode.c:836
 ext4_bread+0x29/0x210 fs/ext4/inode.c:888
 ext4_append+0x15d/0x370 fs/ext4/namei.c:67
 ext4_init_new_dir+0x25e/0x4d0 fs/ext4/namei.c:2769
 ext4_mkdir+0x3c8/0xa30 fs/ext4/namei.c:2814
 vfs_mkdir+0x507/0x770 fs/namei.c:3650
 do_mkdirat+0x262/0x2d0 fs/namei.c:3673
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8880205f0880
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 32 bytes inside of
 96-byte region [ffff8880205f0880, ffff8880205f08e0)
The buggy address belongs to the page:
page:00000000babf1d7a refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x205f0
flags: 0xfff00000000200(slab)
raw: 00fff00000000200 0000000000000000 0000000100000001 ffff888010041780
raw: 0000000000000000 0000000080200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880205f0780: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8880205f0800: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
>ffff8880205f0880: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                               ^
 ffff8880205f0900: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
 ffff8880205f0980: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
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