[v4,1/4] Bluetooth: Fix potential double free caused by hci_conn_unlink

Commit Message

Ruihan Li May 3, 2023, 1:39 p.m. UTC

The hci_conn_unlink function is being called by hci_conn_del, which
means it should not call hci_conn_del with the input parameter conn
again. If it does, conn may have already been released when
hci_conn_unlink returns, leading to potential UAF and double-free
issues.

This patch resolves the problem by modifying hci_conn_unlink to release
only conn's child links when necessary, but never release conn itself.

Reported-by: [e-mail]
Closes: https://lore.kernel.org/linux-bluetooth/[e-mail]/
Fixes: 06149746e720 ("Bluetooth: hci_conn: Add support for linking multiple hcon")
Signed-off-by: Ruihan Li <[e-mail]>
Signed-off-by: Luiz Augusto von Dentz <[e-mail]>
---
  * Fix tags in commit messages. No code was changed.

 net/bluetooth/hci_conn.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

Comments

[e-mail] May 3, 2023, 2:38 p.m. UTC | #1

This is automated email and please do not reply to this email!

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=744697

---Test result---

Test Summary:
CheckPatch                    FAIL      3.22 seconds
GitLint                       FAIL      1.40 seconds
SubjectPrefix                 PASS      0.28 seconds
BuildKernel                   PASS      43.05 seconds
CheckAllWarning               PASS      46.73 seconds
CheckSparse                   PASS      54.02 seconds
CheckSmatch                   PASS      143.56 seconds
BuildKernel32                 PASS      42.36 seconds
TestRunnerSetup               PASS      597.83 seconds
TestRunner_l2cap-tester       PASS      21.30 seconds
TestRunner_iso-tester         PASS      28.00 seconds
TestRunner_bnep-tester        PASS      7.24 seconds
TestRunner_mgmt-tester        PASS      146.36 seconds
TestRunner_rfcomm-tester      PASS      11.56 seconds
TestRunner_sco-tester         PASS      10.86 seconds
TestRunner_ioctl-tester       PASS      13.13 seconds
TestRunner_mesh-tester        PASS      9.28 seconds
TestRunner_smp-tester         PASS      10.50 seconds
TestRunner_userchan-tester    PASS      7.56 seconds
IncrementalBuild              PASS      88.80 seconds

Details
##############################
Test: CheckPatch - FAIL
Desc: Run checkpatch.pl script
Output:
[v4,1/4] Bluetooth: Fix potential double free caused by hci_conn_unlink
WARNING: Reported-by: should be immediately followed by Link: with a URL to the report
#82: 
Reported-by: [e-mail]
Closes: https://lore.kernel.org/linux-bluetooth/[e-mail]/

WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
#83: 
Closes: https://lore.kernel.org/linux-bluetooth/[e-mail]/

WARNING: Unknown link reference 'Closes:', use 'Link:' instead
#83: 
Closes: https://lore.kernel.org/linux-bluetooth/[e-mail]/

total: 0 errors, 3 warnings, 0 checks, 33 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

/github/workspace/src/src/13230190.patch has style problems, please review.

NOTE: Ignored message types: UNKNOWN_COMMIT_ID

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.


[v4,2/4] Bluetooth: Refcnt drop must be placed last in hci_conn_unlink
WARNING: Reported-by: should be immediately followed by Link: with a URL to the report
#83: 
Reported-by: Luiz Augusto von Dentz <[e-mail]>
Closes: https://lore.kernel.org/linux-bluetooth/CABBYNZ+1kce8_RJrLNOXd_8=Mdpb=2bx4Nto-hFORk=[e-mail]/

WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
#84: 
Closes: https://lore.kernel.org/linux-bluetooth/CABBYNZ+1kce8_RJrLNOXd_8=Mdpb=2bx4Nto-hFORk=[e-mail]/

WARNING: Unknown link reference 'Closes:', use 'Link:' instead
#84: 
Closes: https://lore.kernel.org/linux-bluetooth/CABBYNZ+1kce8_RJrLNOXd_8=Mdpb=2bx4Nto-hFORk=[e-mail]/

total: 0 errors, 3 warnings, 0 checks, 15 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

/github/workspace/src/src/13230188.patch has style problems, please review.

NOTE: Ignored message types: UNKNOWN_COMMIT_ID

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.


[v4,3/4] Bluetooth: Fix UAF in hci_conn_hash_flush again
WARNING: Reported-by: should be immediately followed by Link: with a URL to the report
#94: 
Reported-by: [e-mail]
Closes: https://lore.kernel.org/linux-bluetooth/[e-mail]/

WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
#95: 
Closes: https://lore.kernel.org/linux-bluetooth/[e-mail]/

WARNING: Unknown link reference 'Closes:', use 'Link:' instead
#95: 
Closes: https://lore.kernel.org/linux-bluetooth/[e-mail]/

total: 0 errors, 3 warnings, 0 checks, 73 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

/github/workspace/src/src/13230191.patch has style problems, please review.

NOTE: Ignored message types: UNKNOWN_COMMIT_ID

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.


##############################
Test: GitLint - FAIL
Desc: Run gitlint
Output:
[v4,1/4] Bluetooth: Fix potential double free caused by hci_conn_unlink

WARNING: I3 - ignore-body-lines: gitlint will be switching from using Python regex 'match' (match beginning) to 'search' (match anywhere) semantics. Please review your ignore-body-lines.regex option accordingly. To remove this warning, set general.regex-style-search=True. More details: https://jorisroovers.github.io/gitlint/configuration/#regex-style-search
13: B1 Line exceeds max length (88>80): "Closes: https://lore.kernel.org/linux-bluetooth/[e-mail]/"
[v4,2/4] Bluetooth: Refcnt drop must be placed last in hci_conn_unlink

WARNING: I3 - ignore-body-lines: gitlint will be switching from using Python regex 'match' (match beginning) to 'search' (match anywhere) semantics. Please review your ignore-body-lines.regex option accordingly. To remove this warning, set general.regex-style-search=True. More details: https://jorisroovers.github.io/gitlint/configuration/#regex-style-search
13: B1 Line exceeds max length (115>80): "Closes: https://lore.kernel.org/linux-bluetooth/CABBYNZ+1kce8_RJrLNOXd_8=Mdpb=2bx4Nto-hFORk=[e-mail]/"
[v4,3/4] Bluetooth: Fix UAF in hci_conn_hash_flush again

WARNING: I3 - ignore-body-lines: gitlint will be switching from using Python regex 'match' (match beginning) to 'search' (match anywhere) semantics. Please review your ignore-body-lines.regex option accordingly. To remove this warning, set general.regex-style-search=True. More details: https://jorisroovers.github.io/gitlint/configuration/#regex-style-search
24: B1 Line exceeds max length (88>80): "Closes: https://lore.kernel.org/linux-bluetooth/[e-mail]/"


---
Regards,
Linux Bluetooth

[e-mail] May 3, 2023, 5:30 p.m. UTC | #2

Hello:

This series was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <[e-mail]>:

On Wed,  3 May 2023 21:39:34 +0800 you wrote:
> The hci_conn_unlink function is being called by hci_conn_del, which
> means it should not call hci_conn_del with the input parameter conn
> again. If it does, conn may have already been released when
> hci_conn_unlink returns, leading to potential UAF and double-free
> issues.
> 
> This patch resolves the problem by modifying hci_conn_unlink to release
> only conn's child links when necessary, but never release conn itself.
> 
> [...]

Here is the summary with links:
  - [v4,1/4] Bluetooth: Fix potential double free caused by hci_conn_unlink
    https://git.kernel.org/bluetooth/bluetooth-next/c/3214238e9dc7
  - [v4,2/4] Bluetooth: Refcnt drop must be placed last in hci_conn_unlink
    https://git.kernel.org/bluetooth/bluetooth-next/c/38e9b45310de
  - [v4,3/4] Bluetooth: Fix UAF in hci_conn_hash_flush again
    https://git.kernel.org/bluetooth/bluetooth-next/c/29f883dcbfd0
  - [v4,4/4] Bluetooth: Unlink CISes when LE disconnects in hci_conn_del
    https://git.kernel.org/bluetooth/bluetooth-next/c/e6e576ec4e72

You are awesome, thank you!

Patch

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 640b951bf..70e1655a9 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1083,8 +1083,18 @@  static void hci_conn_unlink(struct hci_conn *conn)
 	if (!conn->parent) {
 		struct hci_link *link, *t;
 
-		list_for_each_entry_safe(link, t, &conn->link_list, list)
-			hci_conn_unlink(link->conn);
+		list_for_each_entry_safe(link, t, &conn->link_list, list) {
+			struct hci_conn *child = link->conn;
+
+			hci_conn_unlink(child);
+
+			/* Due to race, SCO connection might be not established
+			 * yet at this point. Delete it now, otherwise it is
+			 * possible for it to be stuck and can't be deleted.
+			 */
+			if (child->handle == HCI_CONN_HANDLE_UNSET)
+				hci_conn_del(child);
+		}
 
 		return;
 	}
@@ -1100,13 +1110,6 @@  static void hci_conn_unlink(struct hci_conn *conn)
 
 	kfree(conn->link);
 	conn->link = NULL;
-
-	/* Due to race, SCO connection might be not established
-	 * yet at this point. Delete it now, otherwise it is
-	 * possible for it to be stuck and can't be deleted.
-	 */
-	if (conn->handle == HCI_CONN_HANDLE_UNSET)
-		hci_conn_del(conn);
 }
 
 int hci_conn_del(struct hci_conn *conn)