syzbot


KASAN: use-after-free Read in path_init

Status: auto-closed as invalid on 2019/02/22 10:09
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+ebb37fc8fd7a28c93dec@syzkaller.appspotmail.com
First crash: 2216d, last: 2216d
Discussions (1)
Title Replies (including bot) Last reply
KASAN: use-after-free Read in path_init 0 (1) 2018/04/29 16:31
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in path_init (3) fs 2 1299d 1293d 0/26 auto-closed as invalid on 2020/12/29 19:01
upstream KASAN: use-after-free Read in path_init (2) fs C done 29 1377d 1378d 15/26 fixed on 2020/09/16 22:51

Sample crash report:
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
==================================================================
BUG: KASAN: use-after-free in path_init+0x1675/0x2320 fs/namei.c:2132
Read of size 1 at addr ffff8801c907ae80 by task syz-executor7/4548

CPU: 1 PID: 4548 Comm: syz-executor7 Not tainted 4.17.0-rc2+ #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 path_init+0x1675/0x2320 fs/namei.c:2132
 path_openat+0x1f1/0x4e20 fs/namei.c:3495
 do_filp_open+0x249/0x350 fs/namei.c:3535
 do_sys_open+0x56f/0x740 fs/open.c:1093
 __do_sys_open fs/open.c:1111 [inline]
 __se_sys_open fs/open.c:1106 [inline]
 __x64_sys_open+0x7e/0xc0 fs/open.c:1106
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x453aa0
RSP: 002b:0000000000a3d940 EFLAGS: 00000202 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 000000000000004a RCX: 0000000000453aa0
RDX: 000000000000000c RSI: 0000000000090800 RDI: 0000000000a3f790
RBP: 0000000000a3f790 R08: 0000000000000001 R09: 0000000000e25940
R10: 0000000000000000 R11: 0000000000000202 R12: 00000000000001e4
R13: 0000000000000000 R14: 00000000000001e4 R15: 000000000001b450

Allocated by task 4549:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
 getname_flags+0xd0/0x5a0 fs/namei.c:140
 getname fs/namei.c:211 [inline]
 do_rmdir+0xe3/0x610 fs/namei.c:3878
 __do_sys_rmdir fs/namei.c:3929 [inline]
 __se_sys_rmdir fs/namei.c:3927 [inline]
 __x64_sys_rmdir+0x36/0x40 fs/namei.c:3927
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 4549:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kmem_cache_free+0x86/0x2d0 mm/slab.c:3756
 putname+0xf2/0x130 fs/namei.c:261
 do_rmdir+0x202/0x610 fs/namei.c:3919
 __do_sys_rmdir fs/namei.c:3929 [inline]
 __se_sys_rmdir fs/namei.c:3927 [inline]
 __x64_sys_rmdir+0x36/0x40 fs/namei.c:3927
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801c907ae80
 which belongs to the cache names_cache of size 4096
The buggy address is located 0 bytes inside of
 4096-byte region [ffff8801c907ae80, ffff8801c907be80)
The buggy address belongs to the page:
page:ffffea0007241e80 count:1 mapcount:0 mapping:ffff8801c907ae80 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801c907ae80 0000000000000000 0000000100000001
raw: ffffea0007245ea0 ffffea0006bbc220 ffff8801da988dc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c907ad80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801c907ae00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801c907ae80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801c907af00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c907af80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/04/27 19:28 upstream d8a332730e75 7785e404 .config console log report ci-upstream-kasan-gce
* Struck through repros no longer work on HEAD.