KASAN: use-after-free Read in delete_partition

From: syzbot
Date: Fri Sep 04 2020 - 21:39:34 EST

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Hello,

syzbot found the following issue on:

HEAD commit: f75aef39 Linux 5.9-rc3
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=130c72f5900000
kernel config: https://syzkaller.appspot.com/x/.config?x=3c5f6ce8d5b68299
dashboard link: https://syzkaller.appspot.com/bug?extid=b8639c8dcb5ec4483d4f
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15c43c79900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=173dfa1e900000

The issue was bisected to:

commit cddae808aeb77e5c29d22a8e0dfbdaed413f9e04
Author: Christoph Hellwig <hch@xxxxxx>
Date: Tue Apr 14 07:28:54 2020 +0000

block: pass a hd_struct to delete_partition

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14696476900000
final oops: https://syzkaller.appspot.com/x/report.txt?x=16696476900000
console output: https://syzkaller.appspot.com/x/log.txt?x=12696476900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b8639c8dcb5ec4483d4f@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: cddae808aeb7 ("block: pass a hd_struct to delete_partition")

==================================================================
BUG: KASAN: use-after-free in kobject_put+0x220/0x270 lib/kobject.c:748
Read of size 1 at addr ffff8880978c7a3c by task syz-executor581/7048

CPU: 1 PID: 7048 Comm: syz-executor581 Not tainted 5.9.0-rc3-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+0x198/0x1fd lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
kobject_put+0x220/0x270 lib/kobject.c:748
delete_partition+0x134/0x220 block/partitions/core.c:324
bdev_del_partition+0x18b/0x1d0 block/partitions/core.c:549
blkpg_do_ioctl+0x2d6/0x330 block/ioctl.c:33
blkpg_ioctl block/ioctl.c:69 [inline]
blkdev_ioctl+0x58a/0x700 block/ioctl.c:589
block_ioctl+0xf9/0x140 fs/block_dev.c:1871
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x446959
Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 06 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fcab8868d98 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 0000000000446959
RDX: 0000000020000000 RSI: 0000000000001269 RDI: 0000000000000005
RBP: 00000000006dbc30 R08: 00007fcab8869700 R09: 0000000000000000
R10: 00007fcab8869700 R11: 0000000000000246 R12: 00000000006dbc3c
R13: 00000000000000a9 R14: 00b747111e42e3ec R15: 02ba2b7a04b8ac00

Allocated by task 7050:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
kmem_cache_alloc_trace+0x174/0x2c0 mm/slab.c:3550
kmalloc include/linux/slab.h:554 [inline]
kzalloc include/linux/slab.h:666 [inline]
kobject_create lib/kobject.c:783 [inline]
kobject_create_and_add+0x42/0xb0 lib/kobject.c:809
add_partition+0x989/0xd80 block/partitions/core.c:443
bdev_add_partition+0xb6/0x130 block/partitions/core.c:518
blkpg_do_ioctl+0x2be/0x330 block/ioctl.c:52
blkpg_ioctl block/ioctl.c:69 [inline]
blkdev_ioctl+0x58a/0x700 block/ioctl.c:589
block_ioctl+0xf9/0x140 fs/block_dev.c:1871
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 7049:
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+0xd8/0x120 mm/kasan/common.c:422
__cache_free mm/slab.c:3418 [inline]
kfree+0x10e/0x2b0 mm/slab.c:3756
kobject_cleanup lib/kobject.c:704 [inline]
kobject_release lib/kobject.c:735 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x171/0x270 lib/kobject.c:752
delete_partition+0x134/0x220 block/partitions/core.c:324
bdev_del_partition+0x18b/0x1d0 block/partitions/core.c:549
blkpg_do_ioctl+0x2d6/0x330 block/ioctl.c:33
blkpg_ioctl block/ioctl.c:69 [inline]
blkdev_ioctl+0x58a/0x700 block/ioctl.c:589
block_ioctl+0xf9/0x140 fs/block_dev.c:1871
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
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 ffff8880978c7a00
which belongs to the cache kmalloc-64 of size 64
The buggy address is located 60 bytes inside of
64-byte region [ffff8880978c7a00, ffff8880978c7a40)
The buggy address belongs to the page:
page:00000000d9b3b008 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x978c7
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00027750c8 ffff8880aa041350 ffff8880aa040200
raw: 0000000000000000 ffff8880978c7000 0000000100000020 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880978c7900: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
ffff8880978c7980: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff8880978c7a00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
^
ffff8880978c7a80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
ffff8880978c7b00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================

---
This report is generated by a bot. It may contain errors.
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syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.

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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

Next message: Shawn Guo: "Re: [PATCH v2 0/2] ARM: dts: add Tolino Shine 2 HD"
Previous message: Shawn Guo: "Re: [PATCH] clk: imx: fix composite peripheral flags"
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