syzbot


KASAN: use-after-free Read in squashfs_get_id
Status: fixed on 2021/02/23 13:44
Reported-by: syzbot+c021ba012da41ee9807c@syzkaller.appspotmail.com
Fix commit: 8d9ca7e328ef squashfs: add more sanity checks in id lookup
First crash: 548d, last: 452d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 KASAN: use-after-free Read in squashfs_get_id C 3 499d 553d 1/1 fixed on 2021/02/19 15:06
upstream KASAN: use-after-free Read in squashfs_get_id C error error 6 516d 602d 0/22 upstream: reported C repro on 2020/09/25 16:12

Sample crash report:
wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
==================================================================
BUG: KASAN: use-after-free in squashfs_get_id+0x181/0x1a0 fs/squashfs/id.c:51
Read of size 8 at addr ffff8880afd02300 by task syz-executor182/7993

CPU: 1 PID: 7993 Comm: syz-executor182 Not tainted 4.14.207-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:64 [inline]
 squashfs_read_inode+0x185/0x19e0 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: 0033:0x44dcda
RSP: 002b:00007fff2b2414c8 EFLAGS: 00000293 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff2b241520 RCX: 000000000044dcda
RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007fff2b2414e0
RBP: 0000000000000004 R08: 00007fff2b241520 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 00007fff2b2414e0 R14: 0000000000000000 R15: 0000000020000228

Allocated by task 7993:
 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_array include/linux/slab.h:607 [inline]
 kcalloc include/linux/slab.h:618 [inline]
 squashfs_read_table+0x76/0x18d fs/squashfs/cache.c:430
 squashfs_read_xattr_id_table+0x16a/0x200 fs/squashfs/xattr_id.c:94
 squashfs_fill_super+0xb6c/0x1aa0 fs/squashfs/super.c:233
 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 7993:
 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
 squashfs_read_table+0x127/0x18d fs/squashfs/cache.c:448
 squashfs_read_xattr_id_table+0x16a/0x200 fs/squashfs/xattr_id.c:94
 squashfs_fill_super+0xb6c/0x1aa0 fs/squashfs/super.c:233
 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

The buggy address belongs to the object at ffff8880afd02300
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 32-byte region [ffff8880afd02300, ffff8880afd02320)
The buggy address belongs to the page:
page:ffffea0002bf4080 count:1 mapcount:0 mapping:ffff8880afd02000 index:0xffff8880afd02fc1
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff8880afd02000 ffff8880afd02fc1 000000010000003f
raw: ffffea0002d214a0 ffffea0002bc8760 ffff88813fe821c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880afd02200: fb fb fb fb fc fc fc fc 00 fc fc fc fc fc fc fc
 ffff8880afd02280: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8880afd02300: fb fb fb fb fc fc fc fc 00 fc fc fc fc fc fc fc
                   ^
 ffff8880afd02380: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880afd02400: 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 Title
ci2-linux-4-14 2021/02/23 04:57 linux-4.14.y 29c52025152b 0767f13f .config log report syz C
ci2-linux-4-14 2021/01/18 10:11 linux-4.14.y 2762b48e9611 0767f13f .config log report syz C
ci2-linux-4-14 2020/12/19 07:22 linux-4.14.y 3f2ecb86cb90 0767f13f .config log report syz C
Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2020/11/19 06:44 linux-4.14.y 8961076ed318 0767f13f .config log report syz C