[RFC] Bluetooth: fix race condition in sco_connect()

Commit Message

Dmitry Antipov April 3, 2024, 2:27 p.m. UTC

This patch is intended to fix the race condition between two
'sco_connect()' calls, where two instances of 'struct sco_conn'
are erroneously set up to share the pointer to the same 'struct
sock'. When one of the connections goes away, it destroys an
underlying socket as well, leaving dangling pointer to destroyed
socket within another. Next, if the latter (alive) connection
enters 'sco_sock_timeout()', an attempt to do 'lock_sock()' on
a destroyed socket causes use-after-free write reported by KASAN
at https://syzkaller.appspot.com/bug?extid=4c0d0c4cde787116d465.

Signed-off-by: Dmitry Antipov <[e-mail]>
---
 net/bluetooth/sco.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

[e-mail] April 3, 2024, 2:56 p.m. UTC | #1

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Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=841114

---Test result---

Test Summary:
CheckPatch                    PASS      0.66 seconds
GitLint                       PASS      0.32 seconds
SubjectPrefix                 PASS      0.12 seconds
BuildKernel                   PASS      29.73 seconds
CheckAllWarning               PASS      32.06 seconds
CheckSparse                   WARNING   39.63 seconds
CheckSmatch                   FAIL      34.58 seconds
BuildKernel32                 PASS      28.85 seconds
TestRunnerSetup               PASS      541.12 seconds
TestRunner_l2cap-tester       PASS      24.53 seconds
TestRunner_iso-tester         PASS      31.28 seconds
TestRunner_bnep-tester        PASS      4.85 seconds
TestRunner_mgmt-tester        FAIL      113.37 seconds
TestRunner_rfcomm-tester      PASS      7.55 seconds
TestRunner_sco-tester         PASS      15.03 seconds
TestRunner_ioctl-tester       PASS      7.91 seconds
TestRunner_mesh-tester        PASS      5.98 seconds
TestRunner_smp-tester         PASS      6.95 seconds
TestRunner_userchan-tester    PASS      5.05 seconds
IncrementalBuild              PASS      28.88 seconds

Details
##############################
Test: CheckSparse - WARNING
Desc: Run sparse tool with linux kernel
Output:
net/bluetooth/sco.c: note: in included file:./include/net/bluetooth/hci_core.h:150:35: warning: array of flexible structures
##############################
Test: CheckSmatch - FAIL
Desc: Run smatch tool with source
Output:

Segmentation fault (core dumped)
make[4]: *** [scripts/Makefile.build:244: net/bluetooth/hci_core.o] Error 139
make[4]: *** Deleting file 'net/bluetooth/hci_core.o'
make[3]: *** [scripts/Makefile.build:485: net/bluetooth] Error 2
make[2]: *** [scripts/Makefile.build:485: net] Error 2
make[2]: *** Waiting for unfinished jobs....
Segmentation fault (core dumped)
make[4]: *** [scripts/Makefile.build:244: drivers/bluetooth/bcm203x.o] Error 139
make[4]: *** Deleting file 'drivers/bluetooth/bcm203x.o'
make[4]: *** Waiting for unfinished jobs....
make[3]: *** [scripts/Makefile.build:485: drivers/bluetooth] Error 2
make[2]: *** [scripts/Makefile.build:485: drivers] Error 2
make[1]: *** [/github/workspace/src/src/Makefile:1919: .] Error 2
make: *** [Makefile:240: __sub-make] Error 2
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 492, Passed: 488 (99.2%), Failed: 2, Not Run: 2

Failed Test Cases
LL Privacy - Add Device 5 (2 Devices to RL)          Failed       0.167 seconds
LL Privacy - Add Device 6 (RL is full)               Failed       0.186 seconds


---
Regards,
Linux Bluetooth

Patch

diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index 43daf965a01e..f8e5e4c3420f 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -228,7 +228,7 @@  static int sco_chan_add(struct sco_conn *conn, struct sock *sk,
 	int err = 0;
 
 	sco_conn_lock(conn);
-	if (conn->sk)
+	if (conn->sk || sco_pi(sk)->conn)
 		err = -EBUSY;
 	else
 		__sco_chan_add(conn, sk, parent);