From: Norbert Slusarek
mainline inclusion
from mainline-v5.13-rc7
commit 5e87ddbe3942e27e939bdc02deb8579b0cbd8ecc
category: bugfix
issue: #I42GZO
CVE: CVE-2021-34693
--------------------------------
On 64-bit systems, struct bcm_msg_head has an added padding of 4 bytes between
struct members count and ival1. Even though all struct members are initialized,
the 4-byte hole will contain data from the kernel stack. This patch zeroes out
struct bcm_msg_head before usage, preventing infoleaks to userspace.
Fixes: ffd980f976e7 ("[CAN]: Add broadcast manager (bcm) protocol")
Link: https://lore.kernel.org/r/trinity-7c1b2e82-e34f-4885-8060-2cd7a13769ce-16235...
Cc: linux-stable
Signed-off-by: Norbert Slusarek
Acked-by: Oliver Hartkopp
Signed-off-by: Marc Kleine-Budde
Signed-off-by: Yang Yingliang
Reviewed-by: Xiu Jianfeng
Reviewed-by: Yue Haibing
Signed-off-by: Yang Yingliang
Signed-off-by: Yu Changchun
---
net/can/bcm.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 79bb8afa9..c82137fb2 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -393,6 +393,7 @@ static void bcm_tx_timeout_tsklet(unsigned long data)
if (!op->count && (op->flags & TX_COUNTEVT)) {
/* create notification to user */
+ memset(&msg_head, 0, sizeof(msg_head));
msg_head.opcode = TX_EXPIRED;
msg_head.flags = op->flags;
msg_head.count = op->count;
@@ -440,6 +441,7 @@ static void bcm_rx_changed(struct bcm_op *op, struct canfd_frame *data)
/* this element is not throttled anymore */
data->flags &= (BCM_CAN_FLAGS_MASK|RX_RECV);
+ memset(&head, 0, sizeof(head));
head.opcode = RX_CHANGED;
head.flags = op->flags;
head.count = op->count;
@@ -554,6 +556,7 @@ static void bcm_rx_timeout_tsklet(unsigned long data)
struct bcm_msg_head msg_head;
/* create notification to user */
+ memset(&msg_head, 0, sizeof(msg_head));
msg_head.opcode = RX_TIMEOUT;
msg_head.flags = op->flags;
msg_head.count = op->count;
--
2.22.0
