syzbot


KASAN: slab-out-of-bounds Read in squashfs_get_id

Status: fixed on 2021/02/23 13:44
Reported-by: syzbot+bcbc661df46657d0fa4f@syzkaller.appspotmail.com
Fix commit: 8d9ca7e328ef squashfs: add more sanity checks in id lookup
First crash: 863d, last: 710d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-out-of-bounds Read in squashfs_get_id C error done 77 724d 860d 22/24 fixed on 2021/03/11 23:45
linux-4.19 KASAN: slab-out-of-bounds Read in squashfs_get_id C 58 717d 861d 1/1 fixed on 2021/02/19 15:06

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in squashfs_get_id+0x181/0x1a0 fs/squashfs/id.c:51
Read of size 8 at addr ffff8880a5069d18 by task syz-executor423/7995

CPU: 1 PID: 7995 Comm: syz-executor423 Not tainted 4.14.213-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
 squashfs_get_id+0x181/0x1a0 fs/squashfs/id.c:51
 squashfs_new_inode fs/squashfs/inode.c:68 [inline]
 squashfs_read_inode+0x1b6/0x19e0 fs/squashfs/inode.c:133
 squashfs_fill_super+0x1501/0x1aa0 fs/squashfs/super.c:318
 mount_bdev+0x2b3/0x360 fs/super.c:1134
 mount_fs+0x92/0x2a0 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2549 [inline]
 do_mount+0xe53/0x2a00 fs/namespace.c:2879
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xa8/0x120 fs/namespace.c:3072
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x446d2a
RSP: 002b:00007ffeced0c068 EFLAGS: 00000293 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffeced0c0c0 RCX: 0000000000446d2a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffeced0c080
RBP: 00007ffeced0c080 R08: 00007ffeced0c0c0 R09: 00007ffe00000015
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 0000000000000004 R14: 0000000000000003 R15: 0000000000000003

Allocated by task 7995:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15a/0x400 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 squashfs_read_table+0x37/0x18d fs/squashfs/cache.c:426
 squashfs_read_id_index_table+0x97/0xe0 fs/squashfs/id.c:90
 squashfs_fill_super+0xc2c/0x1aa0 fs/squashfs/super.c:246
 mount_bdev+0x2b3/0x360 fs/super.c:1134
 mount_fs+0x92/0x2a0 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2549 [inline]
 do_mount+0xe53/0x2a00 fs/namespace.c:2879
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xa8/0x120 fs/namespace.c:3072
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 6246:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 aa_free_task_context+0xda/0x130 security/apparmor/context.c:54
 apparmor_cred_free+0x34/0x70 security/apparmor/lsm.c:58
 security_cred_free+0x71/0xb0 security/security.c:1003
 put_cred_rcu+0xe3/0x300 kernel/cred.c:117
 __put_cred+0x1a1/0x210 kernel/cred.c:151
 put_cred include/linux/cred.h:271 [inline]
 SYSC_faccessat fs/open.c:444 [inline]
 SyS_faccessat+0x52a/0x680 fs/open.c:353
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff8880a5069d00
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 24 bytes inside of
 32-byte region [ffff8880a5069d00, ffff8880a5069d20)
The buggy address belongs to the page:
page:ffffea0002941a40 count:1 mapcount:0 mapping:ffff8880a5069000 index:0xffff8880a5069fc1
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff8880a5069000 ffff8880a5069fc1 0000000100000014
raw: ffffea00029343e0 ffffea0002941460 ffff88813fe801c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a5069c00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a5069c80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8880a5069d00: 00 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc
                            ^
 ffff8880a5069d80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a5069e00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================

Fix bisection attempts:
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Title
ci2-linux-4-14 2021/02/22 15:36 linux-4.14.y 29c52025152b 0fa352f2 .config console log report syz C
ci2-linux-4-14 2020/11/03 07:46 linux-4.14.y 2b7915014161 1a3f9408 .config console log report syz C
* Struck through repros no longer work on HEAD.
Crashes (11):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Title
ci2-linux-4-14 2020/12/30 07:02 linux-4.14.y 1752938529c6 0fa352f2 .config console log report syz C
ci2-linux-4-14 2020/12/09 07:24 linux-4.14.y 47cbf4cc32db 40cc414d .config console log report syz C
ci2-linux-4-14 2020/10/04 07:24 linux-4.14.y cbfa1702aaf6 1a3f9408 .config console log report syz C
ci2-linux-4-14 2020/09/29 13:06 linux-4.14.y cbfa1702aaf6 1b88c6d5 .config console log report syz C
ci2-linux-4-14 2020/09/27 09:58 linux-4.14.y cbfa1702aaf6 5dd8aee8 .config console log report syz C
ci2-linux-4-14 2020/09/22 06:59 linux-4.14.y cbfa1702aaf6 9e1fa68e .config console log report syz C
ci2-linux-4-14 2021/01/15 12:36 linux-4.14.y f79dc86058bc 65a7a854 .config console log report info
ci2-linux-4-14 2020/12/09 06:39 linux-4.14.y 47cbf4cc32db 40cc414d .config console log report info
ci2-linux-4-14 2020/11/25 17:26 linux-4.14.y 87335852c5d9 3f581b43 .config console log report info
ci2-linux-4-14 2020/11/24 22:50 linux-4.14.y 87335852c5d9 e34b696c .config console log report info
ci2-linux-4-14 2020/09/27 13:08 linux-4.14.y cbfa1702aaf6 5dd8aee8 .config console log report info
* Struck through repros no longer work on HEAD.