[syzbot] KASAN: use-after-free Read in leaf_paste_in_buffer

syzbot
2022-12-01T11:54:50Z

Hello,

syzbot found the following issue on:

HEAD commit: 04aa64375f48 drm/i915: fix TLB invalidation for Gen12 vide..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=120af47b880000
kernel config: https://syzkaller.appspot.com/x/.config?x=2325e409a9a893e1
dashboard link: https://syzkaller.appspot.com/bug?extid=55b82aea13452e3d128f
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=179f39bb880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1082d8d5880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c7931c6633f6/disk-04aa6437.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9f73ec98f0cb/vmlinux-04aa6437.xz
kernel image: https://storage.googleapis.com/syzbot-assets/63f3355b068c/bzImage-04aa6437.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/897f7c1e79f7/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+55b82aea13452e3d128f@syzkaller.appspotmail.com

REISERFS (device loop0): Using r5 hash to sort names
REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.
==================================================================
BUG: KASAN: use-after-free in leaf_paste_in_buffer+0x739/0xca0
Read of size 80 at addr ffff88806fa50fe0 by task syz-executor881/3646

CPU: 1 PID: 3646 Comm: syz-executor881 Not tainted 6.1.0-rc7-syzkaller-00102-g04aa64375f48 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
print_address_description+0x74/0x340 mm/kasan/report.c:284
print_report+0x107/0x1f0 mm/kasan/report.c:395
kasan_report+0xcd/0x100 mm/kasan/report.c:495
kasan_check_range+0x2a7/0x2e0 mm/kasan/generic.c:189
memcpy+0x25/0x60 mm/kasan/shadow.c:65
leaf_paste_in_buffer+0x739/0xca0
leaf_copy_dir_entries+0x6e2/0xbf0 fs/reiserfs/lbalance.c:108
leaf_copy_boundary_item+0xb7c/0x20f0 fs/reiserfs/lbalance.c:168
leaf_copy_items fs/reiserfs/lbalance.c:551 [inline]
leaf_move_items+0xc74/0x1330 fs/reiserfs/lbalance.c:726
leaf_shift_left+0xb7/0x420 fs/reiserfs/lbalance.c:750
balance_leaf_left fs/reiserfs/do_balan.c:616 [inline]
balance_leaf+0x1579/0x123a0 fs/reiserfs/do_balan.c:1409
do_balance+0x2d6/0x8d0 fs/reiserfs/do_balan.c:1888
reiserfs_paste_into_item+0x740/0x880 fs/reiserfs/stree.c:2159
reiserfs_get_block+0x223f/0x5180 fs/reiserfs/inode.c:1069
__block_write_begin_int+0x54c/0x1a80 fs/buffer.c:1991
reiserfs_write_begin+0x247/0x510 fs/reiserfs/inode.c:2775
generic_perform_write+0x2e4/0x5e0 mm/filemap.c:3753
__generic_file_write_iter+0x176/0x400 mm/filemap.c:3881
generic_file_write_iter+0xab/0x310 mm/filemap.c:3913
call_write_iter include/linux/fs.h:2199 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x7dc/0xc50 fs/read_write.c:584
ksys_write+0x177/0x2a0 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ff595fcba39
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffefc311618 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000db17 RCX: 00007ff595fcba39
RDX: 000000000000fea7 RSI: 00000000200001c0 RDI: 0000000000000006
RBP: 0000000000000000 R08: 00007ffefc311640 R09: 00007ffefc311640
R10: 00007ffefc311640 R11: 0000000000000246 R12: 00007ffefc31163c
R13: 00007ffefc311670 R14: 00007ffefc311650 R15: 0000000000000006
</TASK>

The buggy address belongs to the physical page:
page:ffffea0001be9400 refcount:6 mapcount:0 mapping:ffff88801f8128f8 index:0x214 pfn:0x6fa50
memcg:ffff888140150000
aops:def_blk_aops ino:700000
flags: 0xfff00000002010(lru|private|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000002010 ffffea0001be9388 ffffea00007a5508 ffff88801f8128f8
raw: 0000000000000214 ffff88807007fae0 00000006ffffffff ffff888140150000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x148c48(GFP_NOFS|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL|__GFP_MOVABLE), pid 3646, tgid 3646 (syz-executor881), ts 56559691091, free_ts 56351514064
prep_new_page mm/page_alloc.c:2539 [inline]
get_page_from_freelist+0x742/0x7c0 mm/page_alloc.c:4291
__alloc_pages+0x259/0x560 mm/page_alloc.c:5558
folio_alloc+0x1a/0x50 mm/mempolicy.c:2295
filemap_alloc_folio+0x7e/0x1c0 mm/filemap.c:971
__filemap_get_folio+0x898/0x1260 mm/filemap.c:1965
pagecache_get_page+0x28/0x260 mm/folio-compat.c:110
find_or_create_page include/linux/pagemap.h:613 [inline]
grow_dev_page+0xba/0x920 fs/buffer.c:946
grow_buffers fs/buffer.c:1011 [inline]
__getblk_slow fs/buffer.c:1038 [inline]
__getblk_gfp+0x16c/0x290 fs/buffer.c:1333
sb_getblk include/linux/buffer_head.h:356 [inline]
get_empty_nodes+0x68a/0xd00 fs/reiserfs/fix_node.c:890
fix_nodes+0x25e8/0x8920 fs/reiserfs/fix_node.c:2662
reiserfs_insert_item+0xa78/0xcb0 fs/reiserfs/stree.c:2240
reiserfs_new_inode+0x11c7/0x1cd0 fs/reiserfs/inode.c:2054
reiserfs_create+0x39a/0x660 fs/reiserfs/namei.c:668
lookup_open fs/namei.c:3413 [inline]
open_last_lookups fs/namei.c:3481 [inline]
path_openat+0x12d0/0x2df0 fs/namei.c:3711
do_filp_open+0x264/0x4f0 fs/namei.c:3741
do_sys_openat2+0x124/0x4e0 fs/open.c:1310
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1459 [inline]
free_pcp_prepare+0x80c/0x8f0 mm/page_alloc.c:1509
free_unref_page_prepare mm/page_alloc.c:3387 [inline]
free_unref_page_list+0xb4/0x7b0 mm/page_alloc.c:3529
release_pages+0x232a/0x25c0 mm/swap.c:1055
__pagevec_release+0x7d/0xf0 mm/swap.c:1075
pagevec_release include/linux/pagevec.h:71 [inline]
folio_batch_release include/linux/pagevec.h:135 [inline]
shmem_undo_range+0x89a/0x2260 mm/shmem.c:946
shmem_truncate_range mm/shmem.c:1034 [inline]
shmem_evict_inode+0x27f/0xab0 mm/shmem.c:1143
evict+0x2a4/0x620 fs/inode.c:664
__dentry_kill+0x3b1/0x5b0 fs/dcache.c:607
dentry_kill+0xbb/0x290
dput+0x1f3/0x410 fs/dcache.c:913
__fput+0x5e4/0x880 fs/file_table.c:328
task_work_run+0x243/0x300 kernel/task_work.c:179
ptrace_notify+0x29a/0x340 kernel/signal.c:2354
ptrace_report_syscall include/linux/ptrace.h:420 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:482 [inline]
syscall_exit_work+0x8c/0xe0 kernel/entry/common.c:251
syscall_exit_to_user_mode_prepare+0x63/0xc0 kernel/entry/common.c:278
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0xa/0x60 kernel/entry/common.c:296

Memory state around the buggy address:
ffff88806fa50f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88806fa50f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88806fa51000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88806fa51080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88806fa51100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

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