general protection fault in vsscanf

general protection fault in vsscanf
Status: fixed on 2018/09/03 14:47
Reported-by: syzbot+0ec640a6eebcf1c82417@syzkaller.appspotmail.com
Fix commit: 10aa1452 9p: fix multiple NULL-pointer-dereferences
First crash: 1072d, last: 1041d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
android-49	general protection fault in vsscanf	C			6	1022d	794d	0/3	public: reported C repro on 2019/04/14 00:00

Sample crash report:

random: sshd: uninitialized urandom read (32 bytes read)
FAT-fs (loop0): bogus number of reserved sectors
FAT-fs (loop0): Can't find a valid FAT filesystem
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
CPU: 1 PID: 4364 Comm: syz-executor208 Not tainted 4.18.0-rc8+ #182
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:vsscanf+0x3c1/0x2af0 lib/vsprintf.c:2966
Code: fa 44 89 ee bf 6e 00 00 00 e8 4b 7a d4 fa 41 80 fd 6e 0f 84 ce 02 00 00 e8 6c 79 d4 fa 4c 89 f0 4c 89 f2 48 c1 e8 03 83 e2 07 <42> 0f b6 04 38 38 d0 7f 08 84 c0 0f 85 e8 1c 00 00 45 0f b6 26 31 
RSP: 0018:ffff8801b7a6f0e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffff8785bf81 RCX: ffffffff86a79ed5
RDX: 0000000000000000 RSI: ffffffff86a79ee4 RDI: 0000000000000001
RBP: ffff8801b7a6f2b0 R08: ffff8801bcb28080 R09: ffff8801b7a6f4a4
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff8785bf81
R13: 0000000000000064 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000001e6a880(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000b44e80 CR3: 00000001b9b24000 CR4: 00000000001406e0
Call Trace:
 sscanf+0xab/0xe0 lib/vsprintf.c:3172
 valid_ipaddr4 net/9p/trans_fd.c:903 [inline]
 p9_fd_create_tcp+0x113/0x8a0 net/9p/trans_fd.c:943
 p9_client_create+0x8ed/0x1770 net/9p/client.c:1063
 v9fs_session_init+0x21a/0x1a80 fs/9p/v9fs.c:400
 v9fs_mount+0x7c/0x900 fs/9p/vfs_super.c:135
 mount_fs+0xae/0x328 fs/super.c:1277
 vfs_kern_mount.part.34+0xdc/0x4e0 fs/namespace.c:1037
 vfs_kern_mount fs/namespace.c:1027 [inline]
 do_new_mount fs/namespace.c:2518 [inline]
 do_mount+0x581/0x30e0 fs/namespace.c:2848
 ksys_mount+0x12d/0x140 fs/namespace.c:3064
 __do_sys_mount fs/namespace.c:3078 [inline]
 __se_sys_mount fs/namespace.c:3075 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3075
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x444239
Code: 0d d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 db d7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007ffcc8483028 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 0000000000444239
RDX: 0000000020000040 RSI: 00000000200000c0 RDI: 0000000000000000
RBP: 00000000006cf018 R08: 00000000200001c0 R09: 0000000020000240
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000000401ea0
R13: 0000000000401f30 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
---[ end trace eb82439475c6d986 ]---
RIP: 0010:vsscanf+0x3c1/0x2af0 lib/vsprintf.c:2966
Code: fa 44 89 ee bf 6e 00 00 00 e8 4b 7a d4 fa 41 80 fd 6e 0f 84 ce 02 00 00 e8 6c 79 d4 fa 4c 89 f0 4c 89 f2 48 c1 e8 03 83 e2 07 <42> 0f b6 04 38 38 d0 7f 08 84 c0 0f 85 e8 1c 00 00 45 0f b6 26 31 
RSP: 0018:ffff8801b7a6f0e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffff8785bf81 RCX: ffffffff86a79ed5
RDX: 0000000000000000 RSI: ffffffff86a79ee4 RDI: 0000000000000001
RBP: ffff8801b7a6f2b0 R08: ffff8801bcb28080 R09: ffff8801b7a6f4a4
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff8785bf81
R13: 0000000000000064 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000001e6a880(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000b44e80 CR3: 00000001b9b24000 CR4: 00000000001406e0

Crashes (7):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro
ci-upstream-kasan-gce-root	2018/08/09 21:59	upstream	112cbae2	1fb62d58	.config	log	report	syz	C
ci-upstream-kasan-gce-root	2018/07/11 17:08	upstream	1e09177a	2e0e3130	.config	log	report	syz	C
ci-upstream-kasan-gce	2018/07/11 02:52	upstream	30c2c32d	2e0e3130	.config	log	report	syz	C
ci-upstream-kasan-gce-386	2018/07/10 13:08	upstream	092150a2	9fa03fa5	.config	log	report	syz	C
ci-upstream-linux-next-kasan-gce-root	2018/07/14 02:58	linux-next	483d835c	92a49505	.config	log	report	syz	C
ci-upstream-kasan-gce-root	2018/08/09 07:47	upstream	fedb8da9	2eeda842	.config	log	report
ci-upstream-kasan-gce-root	2018/08/09 03:22	upstream	fedb8da9	2eeda842	.config	log	report