Re: [syzbot] KASAN: slab-out-of-bounds Read in hex_dump_to_buffer

From: syzbot
Date: Sun Oct 02 2022 - 15:29:52 EST

syzbot has found a reproducer for the following issue on:

HEAD commit: b357fd1c2afc Merge tag 'usb-6.0-final' of git://git.kernel..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=15677614880000
kernel config: https://syzkaller.appspot.com/x/.config?x=a1992c90769e07
dashboard link: https://syzkaller.appspot.com/bug?extid=489783e0c22fbb27d8e9
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17e2eeb8880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1201c8cc880000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+489783e0c22fbb27d8e9@xxxxxxxxxxxxxxxxxxxxxxxxx

ffff88806c856a20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
ffff88806c856a30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
==================================================================
BUG: KASAN: slab-out-of-bounds in hex_dump_to_buffer+0xdc1/0xdf0 lib/hexdump.c:193
Read of size 1 at addr ffff88806c856a40 by task syz-executor371/3608

CPU: 1 PID: 3608 Comm: syz-executor371 Not tainted 6.0.0-rc7-syzkaller-00239-gb357fd1c2afc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:317 [inline]
print_report.cold+0x2ba/0x6e9 mm/kasan/report.c:433
kasan_report+0xb1/0x1e0 mm/kasan/report.c:495
hex_dump_to_buffer+0xdc1/0xdf0 lib/hexdump.c:193
print_hex_dump+0x12f/0x1d0 lib/hexdump.c:276
ea_get.cold+0xaa/0x190 fs/jfs/xattr.c:561
__jfs_getxattr+0xc4/0x3d0 fs/jfs/xattr.c:807
jfs_xattr_get+0x39/0x50 fs/jfs/xattr.c:931
__vfs_getxattr+0xd9/0x140 fs/xattr.c:411
inode_doinit_use_xattr+0xb5/0x340 security/selinux/hooks.c:1321
inode_doinit_with_dentry+0xcd3/0x12e0 security/selinux/hooks.c:1443
selinux_d_instantiate+0x23/0x30 security/selinux/hooks.c:6327
security_d_instantiate+0x50/0xe0 security/security.c:2056
d_splice_alias+0x8c/0xc80 fs/dcache.c:3155
jfs_lookup+0x20c/0x2f0 fs/jfs/namei.c:1467
lookup_open.isra.0+0x76a/0x12a0 fs/namei.c:3391
open_last_lookups fs/namei.c:3481 [inline]
path_openat+0x996/0x28f0 fs/namei.c:3688
do_filp_open+0x1b6/0x400 fs/namei.c:3718
do_sys_openat2+0x16d/0x4c0 fs/open.c:1313
do_sys_open fs/open.c:1329 [inline]
__do_sys_open fs/open.c:1337 [inline]
__se_sys_open fs/open.c:1333 [inline]
__x64_sys_open+0x119/0x1c0 fs/open.c:1333
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7feb33d6a0c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff94f813e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007feb33d6a0c9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000340
RBP: 00007feb33d29890 R08: 00005555560782c0 R09: 0000000000000000
R10: 00007fff94f812b0 R11: 0000000000000246 R12: 00000000f8008000
R13: 0000000000000000 R14: 00080000000000fc R15: 0000000000000000
</TASK>

Allocated by task 3608:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:437 [inline]
__kasan_slab_alloc+0x85/0xb0 mm/kasan/common.c:470
kasan_slab_alloc include/linux/kasan.h:224 [inline]
slab_post_alloc_hook mm/slab.h:727 [inline]
slab_alloc mm/slab.c:3294 [inline]
__kmem_cache_alloc_lru mm/slab.c:3471 [inline]
kmem_cache_alloc_lru+0x23d/0x860 mm/slab.c:3498
alloc_inode_sb include/linux/fs.h:3103 [inline]
jfs_alloc_inode+0x23/0x60 fs/jfs/super.c:105
alloc_inode+0x61/0x230 fs/inode.c:260
iget_locked+0x1b7/0x6f0 fs/inode.c:1287
jfs_iget+0x1a/0x4d0 fs/jfs/inode.c:29
jfs_lookup+0x246/0x2f0 fs/jfs/namei.c:1462
lookup_open.isra.0+0x76a/0x12a0 fs/namei.c:3391
open_last_lookups fs/namei.c:3481 [inline]
path_openat+0x996/0x28f0 fs/namei.c:3688
do_filp_open+0x1b6/0x400 fs/namei.c:3718
do_sys_openat2+0x16d/0x4c0 fs/open.c:1313
do_sys_open fs/open.c:1329 [inline]
__do_sys_open fs/open.c:1337 [inline]
__se_sys_open fs/open.c:1333 [inline]
__x64_sys_open+0x119/0x1c0 fs/open.c:1333
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88806c856180
which belongs to the cache jfs_ip of size 2240
The buggy address is located 0 bytes to the right of
2240-byte region [ffff88806c856180, ffff88806c856a40)

The buggy address belongs to the physical page:
page:ffffea0001b21580 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88806c856fff pfn:0x6c856
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0001b21488 ffff88801ba2b150 ffff88801ba26a00
raw: ffff88806c856fff ffff88806c856180 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Reclaimable, gfp_mask 0x242050(__GFP_IO|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE|__GFP_RECLAIMABLE), pid 3608, tgid 3608 (syz-executor371), ts 53583161798, free_ts 12386078992
prep_new_page mm/page_alloc.c:2532 [inline]
get_page_from_freelist+0x109b/0x2ce0 mm/page_alloc.c:4283
__alloc_pages+0x1c7/0x510 mm/page_alloc.c:5549
__alloc_pages_node include/linux/gfp.h:243 [inline]
kmem_getpages mm/slab.c:1363 [inline]
cache_grow_begin+0x75/0x360 mm/slab.c:2569
cache_alloc_refill+0x27f/0x380 mm/slab.c:2942
____cache_alloc mm/slab.c:3018 [inline]
____cache_alloc mm/slab.c:3001 [inline]
__do_cache_alloc mm/slab.c:3246 [inline]
slab_alloc mm/slab.c:3287 [inline]
__kmem_cache_alloc_lru mm/slab.c:3471 [inline]
kmem_cache_alloc_lru+0x727/0x860 mm/slab.c:3498
alloc_inode_sb include/linux/fs.h:3103 [inline]
jfs_alloc_inode+0x23/0x60 fs/jfs/super.c:105
alloc_inode+0x61/0x230 fs/inode.c:260
iget_locked+0x1b7/0x6f0 fs/inode.c:1287
jfs_iget+0x1a/0x4d0 fs/jfs/inode.c:29
jfs_lookup+0x246/0x2f0 fs/jfs/namei.c:1462
lookup_open.isra.0+0x76a/0x12a0 fs/namei.c:3391
open_last_lookups fs/namei.c:3481 [inline]
path_openat+0x996/0x28f0 fs/namei.c:3688
do_filp_open+0x1b6/0x400 fs/namei.c:3718
do_sys_openat2+0x16d/0x4c0 fs/open.c:1313
do_sys_open fs/open.c:1329 [inline]
__do_sys_open fs/open.c:1337 [inline]
__se_sys_open fs/open.c:1333 [inline]
__x64_sys_open+0x119/0x1c0 fs/open.c:1333
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1449 [inline]
free_pcp_prepare+0x5e4/0xd20 mm/page_alloc.c:1499
free_unref_page_prepare mm/page_alloc.c:3380 [inline]
free_unref_page+0x19/0x4d0 mm/page_alloc.c:3476
free_contig_range+0xb1/0x180 mm/page_alloc.c:9453
destroy_args+0xa8/0x646 mm/debug_vm_pgtable.c:1031
debug_vm_pgtable+0x2945/0x29d6 mm/debug_vm_pgtable.c:1354
do_one_initcall+0xfe/0x650 init/main.c:1296
do_initcall_level init/main.c:1369 [inline]
do_initcalls init/main.c:1385 [inline]
do_basic_setup init/main.c:1404 [inline]
kernel_init_freeable+0x6b1/0x73a init/main.c:1623
kernel_init+0x1a/0x1d0 init/main.c:1512
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

Memory state around the buggy address:
ffff88806c856900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88806c856980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88806c856a00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
^
ffff88806c856a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88806c856b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================