[v5.15] KASAN: slab-out-of-bounds Write in copy_page_to_iter

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f6f7927ac664 Linux 5.15.127
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=128b0040680000
kernel config: https://syzkaller.appspot.com/x/.config?x=55f355732ad067d7
dashboard link: https://syzkaller.appspot.com/bug?extid=ce454649fe2c764142b5
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ca3051001874/disk-f6f7927a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fb0f8818e6e8/vmlinux-f6f7927a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/05e287cf01c6/Image-f6f7927a.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ce4546...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in _copy_to_iter+0x5f4/0xd04 lib/iov_iter.c:669
Write of size 2048 at addr ffff0000ce29b800 by task kworker/u4:9/8753

CPU: 1 PID: 8753 Comm: kworker/u4:9 Not tainted 5.15.127-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Workqueue: loop0 loop_workfn
Call trace:
dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
print_address_description+0x7c/0x3f0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:434 [inline]
kasan_report+0x174/0x1e4 mm/kasan/report.c:451
kasan_check_range+0x274/0x2b4 mm/kasan/generic.c:189
memcpy+0xb4/0xe8 mm/kasan/shadow.c:66
_copy_to_iter+0x5f4/0xd04 lib/iov_iter.c:669
__copy_page_to_iter lib/iov_iter.c:864 [inline]
copy_page_to_iter+0x850/0xf84 lib/iov_iter.c:889
shmem_file_read_iter+0x52c/0x7b8 mm/shmem.c:2623
do_iter_readv_writev+0x420/0x5f8
do_iter_read+0x1c4/0x67c fs/read_write.c:790
vfs_iter_read+0x88/0xac fs/read_write.c:832
lo_read_simple drivers/block/loop.c:392 [inline]
do_req_filebacked drivers/block/loop.c:663 [inline]
loop_handle_cmd drivers/block/loop.c:2234 [inline]
loop_process_work+0x16b0/0x2790 drivers/block/loop.c:2274
loop_workfn+0x54/0x68 drivers/block/loop.c:2298
process_one_work+0x790/0x11b8 kernel/workqueue.c:2310
worker_thread+0x910/0x1034 kernel/workqueue.c:2457
kthread+0x37c/0x45c kernel/kthread.c:319
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870

Allocated by task 10840:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:434 [inline]
____kasan_kmalloc+0xbc/0xfc mm/kasan/common.c:513
__kasan_kmalloc+0x10/0x1c mm/kasan/common.c:522
kasan_kmalloc include/linux/kasan.h:264 [inline]
__kmalloc+0x29c/0x4c8 mm/slub.c:4407
kmalloc include/linux/slab.h:596 [inline]
hfsplus_read_wrapper+0x494/0xfc8 fs/hfsplus/wrapper.c:183
hfsplus_fill_super+0x2f0/0x167c fs/hfsplus/super.c:413
mount_bdev+0x274/0x370 fs/super.c:1387
hfsplus_mount+0x44/0x58 fs/hfsplus/super.c:641
legacy_get_tree+0xd4/0x16c fs/fs_context.c:611
vfs_get_tree+0x90/0x274 fs/super.c:1517
do_new_mount+0x25c/0x8c4 fs/namespace.c:2994
path_mount+0x590/0x104c fs/namespace.c:3324
do_mount fs/namespace.c:3337 [inline]
__do_sys_mount fs/namespace.c:3545 [inline]
__se_sys_mount fs/namespace.c:3522 [inline]
__arm64_sys_mount+0x510/0x5e0 fs/namespace.c:3522
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

The buggy address belongs to the object at ffff0000ce29b800
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
512-byte region [ffff0000ce29b800, ffff0000ce29ba00)
The buggy address belongs to the page:
page:00000000fc3c25cf refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10e298
head:00000000fc3c25cf order:2 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 dead000000000100 dead000000000122 ffff0000c0002600
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff0000ce29b900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff0000ce29b980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff0000ce29ba00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff0000ce29ba80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff0000ce29bb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.