6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Matt Johnston <matt@xxxxxxxxxxxxxxxxxxxx>
[ Upstream commit df8ce77ba8b7c012a3edd1ca7368b46831341466 ]
Use skb_cow_head() prior to modifying the TX SKB. This is necessary
when the SKB has been cloned, to avoid modifying other shared clones.
Signed-off-by: Matt Johnston <matt@xxxxxxxxxxxxxxxxxxxx>
Fixes: f5b8abf9fc3d ("mctp i2c: MCTP I2C binding driver")
Link: https://patch.msgid.link/20250306-matt-mctp-i2c-cow-v1-1-293827212681@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/net/mctp/mctp-i2c.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/net/mctp/mctp-i2c.c b/drivers/net/mctp/mctp-i2c.c
index e70fb66879941..6622de48fc9e7 100644
--- a/drivers/net/mctp/mctp-i2c.c
+++ b/drivers/net/mctp/mctp-i2c.c
@@ -584,6 +584,7 @@ static int mctp_i2c_header_create(struct sk_buff *skb, struct net_device *dev,
struct mctp_i2c_hdr *hdr;
struct mctp_hdr *mhdr;
u8 lldst, llsrc;
+ int rc;
if (len > MCTP_I2C_MAXMTU)
return -EMSGSIZE;
@@ -594,6 +595,10 @@ static int mctp_i2c_header_create(struct sk_buff *skb, struct net_device *dev,
lldst = *((u8 *)daddr);
llsrc = *((u8 *)saddr);
+ rc = skb_cow_head(skb, sizeof(struct mctp_i2c_hdr));
+ if (rc)
+ return rc;
+
skb_push(skb, sizeof(struct mctp_i2c_hdr));
skb_reset_mac_header(skb);
hdr = (void *)skb_mac_header(skb);
--
2.39.5
