From: Stanley Tng <stng@google.com>
Date: Tue, 11 Dec 2018 22:45:13 +0000 (-0800)
Subject: DO NOT MERGE A security fix to check buffer length in l2c_lcc_proc_pdu
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=c1fcbd5508a75ae3eaf5f311d706d026fee2fe48;hp=d1179759041eb66baf1b5cd398d69ce58849d848;p=android-x86%2Fsystem-bt.git

DO NOT MERGE A security fix to check buffer length in l2c_lcc_proc_pdu

Add check to make sure that data buffer is big enough to read the 2
bytes for length.

Also, fix a regression from the previous CL that checks the buffer length
before doing a memcpy. The previous check is too strict causing valid
sized buffers to be rejected. The length check is incorrect and off by the header size.

Bug: 120665616
Test: Run the SL4A Test for LE CoC, BleCoCTest
Merged-In: I30b7a8af11d3a5f974cb39e06b0e3463bebc8e9a
Change-Id: I30b7a8af11d3a5f974cb39e06b0e3463bebc8e9a
(cherry picked from commit fcb1994de1f6ee34b8dc6804a2b32e20bf138073)
(cherry picked from commit 1f1d8b97d80d25023c4c7b04d2aa18d367f4158d)
(cherry picked from commit 6b2739f309f7719086eb8201b3e1a35ba60035f4)
---

diff --git a/stack/l2cap/l2c_fcr.c b/stack/l2cap/l2c_fcr.c
index 2287e0ad7..4c0fb41f9 100644
--- a/stack/l2cap/l2c_fcr.c
+++ b/stack/l2cap/l2c_fcr.c
@@ -840,7 +840,16 @@ void l2c_lcc_proc_pdu(tL2C_CCB *p_ccb, BT_HDR *p_buf)
 
     if (p_ccb->is_first_seg)
     {
+        if (p_buf->len < sizeof(sdu_length)) {
+          L2CAP_TRACE_ERROR("%s: buffer length=%d too small. Need at least 2.",
+                            __func__, p_buf->len);
+          android_errorWriteWithInfoLog(0x534e4554, "120665616", -1, NULL, 0);
+          /* Discard the buffer */
+          osi_free(p_buf);
+          return;
+        }
         STREAM_TO_UINT16(sdu_length, p);
+
         /* Check the SDU Length with local MTU size */
         if (sdu_length > p_ccb->local_conn_cfg.mtu)
         {
@@ -849,6 +858,9 @@ void l2c_lcc_proc_pdu(tL2C_CCB *p_ccb, BT_HDR *p_buf)
             return;
         }
 
+        p_buf->len -= sizeof(sdu_length);
+        p_buf->offset += sizeof(sdu_length);
+
         if (sdu_length < p_buf->len) {
             L2CAP_TRACE_ERROR("%s: Invalid sdu_length: %d", __func__, sdu_length);
             android_errorWriteWithInfoLog(0x534e4554, "112321180", -1, NULL, 0);
@@ -868,8 +880,6 @@ void l2c_lcc_proc_pdu(tL2C_CCB *p_ccb, BT_HDR *p_buf)
         p_data->len = 0;
         p_ccb->ble_sdu_length = sdu_length;
         L2CAP_TRACE_DEBUG ("%s SDU Length = %d",__func__,sdu_length);
-        p_buf->len -= sizeof(sdu_length);
-        p_buf->offset += sizeof(sdu_length);
         p_data->offset = 0;
     } else {
       p_data = p_ccb->ble_sdu;