[syzbot] [btrfs?] KASAN: use-after-free Read in btrfs_test_super

From: syzbot
Date: Mon Aug 28 2023 - 23:29:08 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 626932085009 Add linux-next specific files for 20230825
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15b1c0c0680000
kernel config: https://syzkaller.appspot.com/x/.config?x=8a8c992a790e5073
dashboard link: https://syzkaller.appspot.com/bug?extid=65bb53688b6052f09c28
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=126ab89fa80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10c9371fa80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/46ec18b3c2fb/disk-62693208.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b4ea0cb78498/vmlinux-62693208.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5fb3938c7272/bzImage-62693208.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/29599ed4793a/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+65bb53688b6052f09c28@xxxxxxxxxxxxxxxxxxxxxxxxx

loop0: detected capacity change from 0 to 32768
BTRFS: device fsid d552757d-9c39-40e3-95f0-16d819589928 devid 1 transid 8 /dev/loop0 scanned by syz-executor324 (6049)
==================================================================
BUG: KASAN: use-after-free in btrfs_test_super+0x9b/0xa0 fs/btrfs/super.c:1348
Read of size 8 at addr ffff88807812d110 by task syz-executor324/6049

CPU: 0 PID: 6049 Comm: syz-executor324 Not tainted 6.5.0-rc7-next-20230825-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xc4/0x620 mm/kasan/report.c:475
kasan_report+0xda/0x110 mm/kasan/report.c:588
btrfs_test_super+0x9b/0xa0 fs/btrfs/super.c:1348
sget+0x3de/0x610 fs/super.c:861
btrfs_mount_root+0x692/0xdd0 fs/btrfs/super.c:1508
legacy_get_tree+0x109/0x220 fs/fs_context.c:638
vfs_get_tree+0x8c/0x370 fs/super.c:1713
fc_mount fs/namespace.c:1112 [inline]
vfs_kern_mount.part.0+0xcb/0x170 fs/namespace.c:1142
vfs_kern_mount+0x3f/0x60 fs/namespace.c:1129
btrfs_mount+0x292/0xb10 fs/btrfs/super.c:1585
legacy_get_tree+0x109/0x220 fs/fs_context.c:638
vfs_get_tree+0x8c/0x370 fs/super.c:1713
do_new_mount fs/namespace.c:3335 [inline]
path_mount+0x1492/0x1ed0 fs/namespace.c:3662
do_mount fs/namespace.c:3675 [inline]
__do_sys_mount fs/namespace.c:3884 [inline]
__se_sys_mount fs/namespace.c:3861 [inline]
__x64_sys_mount+0x293/0x310 fs/namespace.c:3861
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f4920f7088a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 3e 06 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4920f29088 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f4920f7088a
RDX: 00000000200055c0 RSI: 0000000020005600 RDI: 00007f4920f290a0
RBP: 00007f4920f290a0 R08: 00007f4920f290e0 R09: 00000000000055a2
R10: 0000000000000000 R11: 0000000000000282 R12: 00007f4920f290e0
R13: 0000000000000000 R14: 0000000000000003 R15: 0000000001000000
</TASK>

The buggy address belongs to the physical page:
page:ffffea0001e04b40 refcount:0 mapcount:0 mapping:0000000000000000 index:0x400000000 pfn:0x7812d
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000400000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x152dc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_ZERO), pid 6045, tgid 6043 (syz-executor324), ts 596852111149, free_ts 598062789716
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x2cf/0x340 mm/page_alloc.c:1530
prep_new_page mm/page_alloc.c:1537 [inline]
get_page_from_freelist+0xf17/0x2e50 mm/page_alloc.c:3200
__alloc_pages+0x1d0/0x4a0 mm/page_alloc.c:4456
__alloc_pages_node include/linux/gfp.h:237 [inline]
alloc_pages_node include/linux/gfp.h:260 [inline]
__kmalloc_large_node+0x87/0x1c0 mm/slab_common.c:1164
__do_kmalloc_node mm/slab_common.c:1011 [inline]
__kmalloc_node.cold+0x5/0xdd mm/slab_common.c:1030
kmalloc_node include/linux/slab.h:619 [inline]
kvmalloc_node+0x6f/0x1a0 mm/util.c:607
kvmalloc include/linux/slab.h:737 [inline]
kvzalloc include/linux/slab.h:745 [inline]
btrfs_mount_root+0x130/0xdd0 fs/btrfs/super.c:1466
legacy_get_tree+0x109/0x220 fs/fs_context.c:638
vfs_get_tree+0x8c/0x370 fs/super.c:1713
fc_mount fs/namespace.c:1112 [inline]
vfs_kern_mount.part.0+0xcb/0x170 fs/namespace.c:1142
vfs_kern_mount+0x3f/0x60 fs/namespace.c:1129
btrfs_mount+0x292/0xb10 fs/btrfs/super.c:1585
legacy_get_tree+0x109/0x220 fs/fs_context.c:638
vfs_get_tree+0x8c/0x370 fs/super.c:1713
do_new_mount fs/namespace.c:3335 [inline]
path_mount+0x1492/0x1ed0 fs/namespace.c:3662
do_mount fs/namespace.c:3675 [inline]
__do_sys_mount fs/namespace.c:3884 [inline]
__se_sys_mount fs/namespace.c:3861 [inline]
__x64_sys_mount+0x293/0x310 fs/namespace.c:3861
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1130 [inline]
free_unref_page_prepare+0x476/0xa40 mm/page_alloc.c:2342
free_unref_page+0x33/0x3b0 mm/page_alloc.c:2435
kvfree+0x47/0x50 mm/util.c:653
deactivate_locked_super+0xa0/0x2d0 fs/super.c:454
deactivate_super+0xde/0x100 fs/super.c:504
cleanup_mnt+0x222/0x3d0 fs/namespace.c:1254
task_work_run+0x14d/0x240 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
exit_to_user_mode_prepare+0x210/0x240 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x1d/0x60 kernel/entry/common.c:296
do_syscall_64+0x44/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
ffff88807812d000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88807812d080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88807812d100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88807812d180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88807812d200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

---
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Next message: Baolin Wang: "Re: [PATCH v2 3/7] mm/compaction: correctly return failure with bogus compound_order in strict mode"
Previous message: Chen Ni: "[PATCH v2] nvdimm: of_pmem: Check return value and add kfree for kstrdup"
Next in thread: Siddh Raman Pant: "Re: [syzbot] [btrfs?] KASAN: use-after-free Read in btrfs_test_super"
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