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BUG: KASAN: slab-out-of-bounds in ovl_check_fb_len+0x171/0x1a0 fs/overlayfs/namei.c:89
Read of size 1 at addr ffff8880aa03044d by task syz-executor.4/13736

CPU: 0 PID: 13736 Comm: syz-executor.4 Not tainted 5.7.0-rc6-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+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:382
 __kasan_report.cold+0x20/0x38 mm/kasan/report.c:511
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 ovl_check_fb_len+0x171/0x1a0 fs/overlayfs/namei.c:89
 ovl_check_fh_len fs/overlayfs/overlayfs.h:358 [inline]
 ovl_fh_to_dentry+0x1ab/0x814 fs/overlayfs/export.c:812
 exportfs_decode_fh+0x11f/0x717 fs/exportfs/expfs.c:434
 do_handle_to_path fs/fhandle.c:152 [inline]
 handle_to_path fs/fhandle.c:207 [inline]
 do_handle_open+0x2b5/0x770 fs/fhandle.c:223
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45ca29
Code: 0d 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f441b1f9c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000130
RAX: ffffffffffffffda RBX: 00000000004f6d00 RCX: 000000000045ca29
RDX: 0000000000000000 RSI: 0000000020000100 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000077b R14: 00000000004ca4e6 R15: 00007f441b1fa6d4

Allocated by task 13736:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc mm/kasan/common.c:495 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x161/0x7a0 mm/slab.c:3665
 kmalloc include/linux/slab.h:560 [inline]
 handle_to_path fs/fhandle.c:192 [inline]
 do_handle_open+0xfd/0x770 fs/fhandle.c:223
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 13373:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x109/0x2b0 mm/slab.c:3757
 do_delayed_call include/linux/delayed_call.h:28 [inline]
 put_link fs/namei.c:916 [inline]
 walk_component+0x24b/0x6a0 fs/namei.c:1851
 link_path_walk.part.0+0x4f1/0xb50 fs/namei.c:2166
 link_path_walk fs/namei.c:2098 [inline]
 path_openat+0x25a/0x27d0 fs/namei.c:3342
 do_filp_open+0x192/0x260 fs/namei.c:3373
 do_sys_openat2+0x585/0x7d0 fs/open.c:1148
 do_sys_open+0xc3/0x140 fs/open.c:1164
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

The buggy address belongs to the object at ffff8880aa030440
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 13 bytes inside of
 32-byte region [ffff8880aa030440, ffff8880aa030460)
The buggy address belongs to the page:
page:ffffea0002a80c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880aa030fc1
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00029e4908 ffffea0002875888 ffff8880aa0001c0
raw: ffff8880aa030fc1 ffff8880aa030000 000000010000003f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880aa030300: 00 00 00 06 fc fc fc fc 00 00 00 03 fc fc fc fc
 ffff8880aa030380: 00 00 00 fc fc fc fc fc 00 00 00 06 fc fc fc fc
>ffff8880aa030400: fb fb fb fb fc fc fc fc 00 02 fc fc fc fc fc fc
                                              ^
 ffff8880aa030480: 00 00 00 fc fc fc fc fc 00 00 00 00 fc fc fc fc
 ffff8880aa030500: 00 00 06 fc fc fc fc fc 00 00 00 02 fc fc fc fc
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