syzbot


KASAN: stack-out-of-bounds Read in ext4_symlink

Status: fixed on 2018/08/07 13:43
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+3774c2af75d1aa1220af@syzkaller.appspotmail.com
Fix commit: 99ba2b5aba24 bpf: sockhash, disallow bpf_tcp_close and update in parallel
First crash: 2111d, last: 2111d

Sample crash report:
==================================================================
PANIC: double fault, error_code: 0x0
BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:345 [inline]
BUG: KASAN: stack-out-of-bounds in ext4_symlink+0x6ea/0x1170 fs/ext4/namei.c:3156
CPU: 1 PID: 13473 Comm: syz-executor7 Not tainted 4.18.0-rc3+ #55
Read of size 24 at addr ffff8801ac37c2e0 by task syz-executor1/13506
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

RIP: 0010:__lock_acquire+0x2e/0x5020 kernel/locking/lockdep.c:3294
CPU: 0 PID: 13506 Comm: syz-executor1 Not tainted 4.18.0-rc3+ #55
Code: 41 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
57 
Call Trace:
41 
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
89 
cf 
41 
56 41 
55 
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
49 
89 fd 
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
41 54 
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
45 
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
89 
 memcpy include/linux/string.h:345 [inline]
 ext4_symlink+0x6ea/0x1170 fs/ext4/namei.c:3156
cc 53 
65 
4c 
8b 34 
25 40 
 vfs_symlink+0x37a/0x5d0 fs/namei.c:4137
ee 
 do_symlinkat+0x242/0x2d0 fs/namei.c:4164
01 00 
48 
83 e4 
 __do_sys_symlink fs/namei.c:4183 [inline]
 __se_sys_symlink fs/namei.c:4181 [inline]
 __x64_sys_symlink+0x59/0x80 fs/namei.c:4181
f0 48 
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
81 
ec 60 
03 
00 00 
48 
8b 
45 
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
10 <89> 
RIP: 0033:0x4557e7
94 
Code: 
24 
64 
80 
8b 
00 00 
5d 
00 48 
00 
ba 00 
e9 
00 
14 
00 
fd 
00 
ff 
00 
ff 
fc ff 
4c 
df 
8b 
48 89 
74 
84 
24 
24 
30 
98 
64 
RSP: 0018:ffff8801abd32ee0 EFLAGS: 00010082
c7 
45 
RAX: 0000000000000000 RBX: 1ffff100357a6659 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff88f92620
00 
RBP: ffff8801abd33270 R08: 0000000000000000 R09: 0000000000000000
22 
R10: ffff8801ac7e7be0 R11: ffff88019f3e8b7b R12: 0000000000000000
R13: ffffffff88f92620 R14: ffff88019f3e8400 R15: 0000000000000002
00 00 
FS:  000000000206d940(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
00 bb 
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff8801abd32ed8 CR3: 0000000199809000 CR4: 00000000001406e0
22 
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
00 
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
00 

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/07/15 15:39 bpf-next 13f7432bdd8e 92a49505 .config console log report ci-upstream-bpf-next-kasan-gce
* Struck through repros no longer work on HEAD.