[BlueZ] gatt-server: Flush notify multiple buffer when full and fix overflow

Commit Message

Sebastian Urban June 11, 2021, 8:19 a.m. UTC

This fixes the calculation of available buffer space in
bt_gatt_server_send_notification and sends pending notifications
immediately when there is no more room to add a notification.

Previously there was a buffer overflow caused by incorrect calculation
of available buffer space: data->offset can equal data->len
from a previous call to this function, leading
(data->len - data->offset) to underflow after data->offset += 2.
---
 src/shared/gatt-server.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

Comments

[e-mail] June 11, 2021, 8:42 a.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=498667

---Test result---

Test Summary:
CheckPatch                    FAIL      0.31 seconds
GitLint                       PASS      0.11 seconds
Prep - Setup ELL              PASS      44.15 seconds
Build - Prep                  PASS      0.10 seconds
Build - Configure             PASS      7.14 seconds
Build - Make                  PASS      189.01 seconds
Make Check                    PASS      9.48 seconds
Make Distcheck                PASS      207.31 seconds
Build w/ext ELL - Configure   PASS      6.78 seconds
Build w/ext ELL - Make        PASS      157.09 seconds

Details
##############################
Test: CheckPatch - FAIL
Desc: Run checkpatch.pl script with rule in .checkpatch.conf
Output:
gatt-server: Flush notify multiple buffer when full and fix overflow
WARNING:LONG_LINE_COMMENT: line length of 81 exceeds 80 columns
#28: FILE: src/shared/gatt-server.c:1706:
+		/* Flush buffered data, if this request hits buffer size limit */

WARNING:LONG_LINE: line length of 88 exceeds 80 columns
#29: FILE: src/shared/gatt-server.c:1707:
+		if (data && data->offset > 0 && data->len - data->offset < 4 + length) {

- total: 0 errors, 2 warnings, 38 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.

"[PATCH] gatt-server: Flush notify multiple buffer when full and fix" has style problems, please review.

NOTE: Ignored message types: COMMIT_MESSAGE COMPLEX_MACRO CONST_STRUCT FILE_PATH_CHANGES MISSING_SIGN_OFF PREFER_PACKED SPDX_LICENSE_TAG SPLIT_STRING SSCANF_TO_KSTRTO

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


##############################
Test: GitLint - PASS
Desc: Run gitlint with rule in .gitlint

##############################
Test: Prep - Setup ELL - PASS
Desc: Clone, build, and install ELL

##############################
Test: Build - Prep - PASS
Desc: Prepare environment for build

##############################
Test: Build - Configure - PASS
Desc: Configure the BlueZ source tree

##############################
Test: Build - Make - PASS
Desc: Build the BlueZ source tree

##############################
Test: Make Check - PASS
Desc: Run 'make check'

##############################
Test: Make Distcheck - PASS
Desc: Run distcheck to check the distribution

##############################
Test: Build w/ext ELL - Configure - PASS
Desc: Configure BlueZ source with '--enable-external-ell' configuration

##############################
Test: Build w/ext ELL - Make - PASS
Desc: Build BlueZ source with '--enable-external-ell' configuration



---
Regards,
Linux Bluetooth

Patch

diff --git a/src/shared/gatt-server.c b/src/shared/gatt-server.c
index 970c35f94..e7155f16a 100644
--- a/src/shared/gatt-server.c
+++ b/src/shared/gatt-server.c
@@ -1700,20 +1700,34 @@  bool bt_gatt_server_send_notification(struct bt_gatt_server *server,
 	if (!server || (length && !value))
 		return false;
 
-	if (multiple)
+	if (multiple) {
 		data = server->nfy_mult;
 
+		/* Flush buffered data, if this request hits buffer size limit */
+		if (data && data->offset > 0 && data->len - data->offset < 4 + length) {
+			if (server->nfy_mult->id)
+				timeout_remove(server->nfy_mult->id);
+			notify_multiple(server);
+			data = NULL;
+		}
+	}
+
 	if (!data) {
 		data = new0(struct nfy_mult_data, 1);
 		data->len = bt_att_get_mtu(server->att) - 1;
 		data->pdu = malloc(data->len);
 	}
 
+	if (multiple) {
+		if (data->len - data->offset < 4 + length)
+			return false;
+	} else {
+		if (data->len - data->offset < 2 + length)
+			return false;
+	}
+
 	put_le16(handle, data->pdu + data->offset);
 	data->offset += 2;
-
-	length = MIN(data->len - data->offset, length);
-
 	if (multiple) {
 		put_le16(length, data->pdu + data->offset);
 		data->offset += 2;