[syzbot] [bluetooth?] general protection fault in sco_conn_add

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3674fbf0451d Merge git://git.kernel.org/pub/scm/linux/kern..
git tree: net
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13ab3f4f280000
kernel config: https://syzkaller.appspot.com/x/.config?x=c9bf1936936ca698
dashboard link: https://syzkaller.appspot.com/bug?extid=37acd5d80d00d609d233
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1049b4e2a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=171aa228a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/42ed556782c3/disk-3674fbf0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1913e16e8565/vmlinux-3674fbf0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/469804b58a7c/bzImage-3674fbf0.xz

The issue was bisected to:

commit 06149746e7203d5ffe2d6faf9799ee36203aa8b8
Author: Luiz Augusto von Dentz <luiz.vo...@intel.com>
Date: Tue Apr 11 23:02:22 2023 +0000

Bluetooth: hci_conn: Add support for linking multiple hcon

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=148e6b08a80000
final oops: https://syzkaller.appspot.com/x/report.txt?x=168e6b08a80000
console output: https://syzkaller.appspot.com/x/log.txt?x=128e6b08a80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+37acd5...@syzkaller.appspotmail.com
Fixes: 06149746e720 ("Bluetooth: hci_conn: Add support for linking multiple hcon")

RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f09bc777879
RDX: 0000000000000008 RSI: 0000000020000200 RDI: 0000000000000004
RBP: 0000000000000003 R08: 0000000000000001 R09: 0000000800000015
R10: 0000000000000000 R11: 0000000000000246 R12: 0000555555a6d2b8
R13: 00007ffe17db6850 R14: 0000000000000072 R15: 00007ffe17db6860
</TASK>
general protection fault, probably for non-canonical address 0xdffffc000000013b: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000009d8-0x00000000000009df]
CPU: 1 PID: 5013 Comm: syz-executor238 Not tainted 6.4.0-rc7-syzkaller-01944-g3674fbf0451d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
RIP: 0010:sco_conn_add+0x2a/0x330 net/bluetooth/sco.c:127
Code: 41 57 41 56 41 55 49 89 fd 41 54 55 49 8d ad d8 09 00 00 53 e8 b7 f1 5a f8 48 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 8b 02 00 00 4d 8b a5 d8 09 00 00 4d 85 e4 74 13
RSP: 0018:ffffc90003a8fd50 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888028830000 RCX: 0000000000000000
RDX: 000000000000013b RSI: ffffffff892957a9 RDI: 0000000000000000
RBP: 00000000000009d8 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000010 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8880203cf540 R15: ffff888028830010
FS: 0000555555a6d300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f09bc7db6e3 CR3: 0000000025e98000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
sco_connect net/bluetooth/sco.c:274 [inline]
sco_sock_connect+0x321/0xae0 net/bluetooth/sco.c:610
__sys_connect_file+0x153/0x1a0 net/socket.c:1991
__sys_connect+0x165/0x1a0 net/socket.c:2008
__do_sys_connect net/socket.c:2018 [inline]
__se_sys_connect net/socket.c:2015 [inline]
__x64_sys_connect+0x73/0xb0 net/socket.c:2015
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f09bc777879
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 18 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe17db67f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f09bc777879
RDX: 0000000000000008 RSI: 0000000020000200 RDI: 0000000000000004
RBP: 0000000000000003 R08: 0000000000000001 R09: 0000000800000015
R10: 0000000000000000 R11: 0000000000000246 R12: 0000555555a6d2b8
R13: 00007ffe17db6850 R14: 0000000000000072 R15: 00007ffe17db6860
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:sco_conn_add+0x2a/0x330 net/bluetooth/sco.c:127
Code: 41 57 41 56 41 55 49 89 fd 41 54 55 49 8d ad d8 09 00 00 53 e8 b7 f1 5a f8 48 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 8b 02 00 00 4d 8b a5 d8 09 00 00 4d 85 e4 74 13
RSP: 0018:ffffc90003a8fd50 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888028830000 RCX: 0000000000000000
RDX: 000000000000013b RSI: ffffffff892957a9 RDI: 0000000000000000
RBP: 00000000000009d8 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000010 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8880203cf540 R15: ffff888028830010
FS: 0000555555a6d300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005653cab3d008 CR3: 0000000025e98000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 41 57 push %r15
2: 41 56 push %r14
4: 41 55 push %r13
6: 49 89 fd mov %rdi,%r13
9: 41 54 push %r12
b: 55 push %rbp
c: 49 8d ad d8 09 00 00 lea 0x9d8(%r13),%rbp
13: 53 push %rbx
14: e8 b7 f1 5a f8 callq 0xf85af1d0
19: 48 89 ea mov %rbp,%rdx
1c: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
23: fc ff df
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 0f 85 8b 02 00 00 jne 0x2bf
34: 4d 8b a5 d8 09 00 00 mov 0x9d8(%r13),%r12
3b: 4d 85 e4 test %r12,%r12
3e: 74 13 je 0x53


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the bug is already fixed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to change bug's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[Hillf Danton]

On Sun, 09 Jul 2023 01:07:58 -0700

> HEAD commit: 3674fbf0451d Merge git://git.kernel.org/pub/scm/linux/kern..
> git tree: net

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=171aa228a80000

Check hcon before adding connection.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git 3674fbf0451d

--- x/net/bluetooth/sco.c
+++ y/net/bluetooth/sco.c
@@ -271,6 +271,8 @@ static int sco_connect(struct sock *sk)
hci_dev_unlock(hdev);
hci_dev_put(hdev);

+ if (!hcon)
+ return -ENOMEM;
conn = sco_conn_add(hcon);
if (!conn) {
hci_conn_drop(hcon);
--

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+37acd5...@syzkaller.appspotmail.com

Tested on:

commit: 3674fbf0 Merge git://git.kernel.org/pub/scm/linux/kern..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
console output: https://syzkaller.appspot.com/x/log.txt?x=161333e8a80000

kernel config: https://syzkaller.appspot.com/x/.config?x=c9bf1936936ca698
dashboard link: https://syzkaller.appspot.com/bug?extid=37acd5d80d00d609d233
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=167f9074a80000

Note: testing is done by a robot and is best-effort only.

[Siddh Raman Pant]

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

---
net/bluetooth/hci_conn.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 056f9516e46d..21176908069d 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1684,7 +1684,7 @@ struct hci_conn *hci_connect_sco(struct hci_dev *hdev, int type, bdaddr_t *dst,
if (!link) {
hci_conn_drop(acl);
hci_conn_drop(sco);
- return NULL;
+ return ERR_PTR(-ENOLINK);
}

sco->setting = setting;
@@ -2254,7 +2254,7 @@ struct hci_conn *hci_connect_cis(struct hci_dev *hdev, bdaddr_t *dst,
if (!link) {
hci_conn_drop(le);
hci_conn_drop(cis);
- return NULL;
+ return ERR_PTR(-ENOLINK);
}

/* If LE is already connected and CIS handle is already set proceed to
--
2.40.1

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+37acd5...@syzkaller.appspotmail.com

Tested on:

commit: 3f01e9fe Merge tag 'linux-watchdog-6.5-rc2' of git://w..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=170b4312a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=eaff40ce3a4e79e4

dashboard link: https://syzkaller.appspot.com/bug?extid=37acd5d80d00d609d233
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=166fac98a80000