syzbot


KASAN: slab-out-of-bounds Write in shmem_file_read_iter

Status: upstream: reported C repro on 2024/02/02 14:56
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+ddf6dde5891b1a39037b@syzkaller.appspotmail.com
First crash: 106d, last: 106d
Fix bisection: failed (error log, bisect log)
  
Bug presence (1)
Date Name Commit Repro Result
2024/02/02 upstream (ToT) 021533194476 C [report] KASAN: slab-out-of-bounds Read in generic_perform_write
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: slab-out-of-bounds Write in shmem_file_read_iter origin:upstream C 3 10d 108d 0/3 upstream: reported C repro on 2024/02/01 06:28
upstream KASAN: slab-out-of-bounds Write in shmem_file_read_iter hfs mm C 3 57d 156d 0/26 upstream: reported C repro on 2023/12/14 19:30

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in _copy_to_iter+0x5f4/0xd04 lib/iov_iter.c:669
Write of size 2048 at addr ffff0000c7f88800 by task kworker/u4:2/148

CPU: 0 PID: 148 Comm: kworker/u4:2 Not tainted 5.15.148-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Workqueue: loop4 loop_rootcg_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+0x19f0/0x2798 drivers/block/loop.c:2274
 loop_rootcg_workfn+0x28/0x38 drivers/block/loop.c:2305
 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 4058:
 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+0x278/0x8fc fs/namespace.c:3005
 path_mount+0x594/0x101c fs/namespace.c:3335
 do_mount fs/namespace.c:3348 [inline]
 __do_sys_mount fs/namespace.c:3556 [inline]
 __se_sys_mount fs/namespace.c:3533 [inline]
 __arm64_sys_mount+0x510/0x5e0 fs/namespace.c:3533
 __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:608
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

The buggy address belongs to the object at ffff0000c7f88800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff0000c7f88800, ffff0000c7f88a00)
The buggy address belongs to the page:
page:000000001b9d517e refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff0000c7f8ac00 pfn:0x107f88
head:000000001b9d517e order:2 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 fffffc000336a600 0000000300000003 ffff0000c0002600
raw: ffff0000c7f8a800 0000000080100004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000c7f88900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff0000c7f88980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff0000c7f88a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff0000c7f88a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000c7f88b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
hfsplus: b-tree write err: -5, ino 4
hfsplus: b-tree write err: -5, ino 4

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/02/02 14:55 linux-5.15.y 6139f2a02fe0 d61103fc .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 KASAN: slab-out-of-bounds Write in shmem_file_read_iter
* Struck through repros no longer work on HEAD.