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From 0d328fdf6564b67fc2ec3533e3da201ebabcc9e3 Mon Sep 17 00:00:00 2001
From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Date: Tue, 8 Jun 2021 16:46:49 -0700
Subject: [PATCH] shared/gatt-server: Fix heap overflow when appending prepare
writes
The code shall check if the prepare writes would append more the
allowed maximum attribute length.
Fixes https://github.com/bluez/bluez/security/advisories/GHSA-479m-xcq5-9g2q
Upstream-Status: Backport [https://github.com/bluez/bluez/commit/591c546c536b42bef696d027f64aa22434f8c3f0]
Signed-off-by: Ralph Siemsen <ralph.siemsen@linaro.org>
CVE: CVE-2022-0204
---
src/shared/gatt-server.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/src/shared/gatt-server.c b/src/shared/gatt-server.c
index 0c25a97..20e14bc 100644
--- a/src/shared/gatt-server.c
+++ b/src/shared/gatt-server.c
@@ -816,6 +816,20 @@ static uint8_t authorize_req(struct bt_gatt_server *server,
server->authorize_data);
}
+static uint8_t check_length(uint16_t length, uint16_t offset)
+{
+ if (length > BT_ATT_MAX_VALUE_LEN)
+ return BT_ATT_ERROR_INVALID_ATTRIBUTE_VALUE_LEN;
+
+ if (offset > BT_ATT_MAX_VALUE_LEN)
+ return BT_ATT_ERROR_INVALID_OFFSET;
+
+ if (length + offset > BT_ATT_MAX_VALUE_LEN)
+ return BT_ATT_ERROR_INVALID_ATTRIBUTE_VALUE_LEN;
+
+ return 0;
+}
+
static void write_cb(struct bt_att_chan *chan, uint8_t opcode, const void *pdu,
uint16_t length, void *user_data)
{
@@ -846,6 +860,10 @@ static void write_cb(struct bt_att_chan *chan, uint8_t opcode, const void *pdu,
(opcode == BT_ATT_OP_WRITE_REQ) ? "Req" : "Cmd",
handle);
+ ecode = check_length(length, 0);
+ if (ecode)
+ goto error;
+
ecode = check_permissions(server, attr, BT_ATT_PERM_WRITE_MASK);
if (ecode)
goto error;
@@ -1353,6 +1371,10 @@ static void prep_write_cb(struct bt_att_chan *chan, uint8_t opcode,
util_debug(server->debug_callback, server->debug_data,
"Prep Write Req - handle: 0x%04x", handle);
+ ecode = check_length(length, offset);
+ if (ecode)
+ goto error;
+
ecode = check_permissions(server, attr, BT_ATT_PERM_WRITE_MASK);
if (ecode)
goto error;
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