6.6-stable review patch. If anyone has any objections, please let me know.
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From: Matt Johnston matt@codeconstruct.com.au
[ 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@codeconstruct.com.au Fixes: f5b8abf9fc3d ("mctp i2c: MCTP I2C binding driver") Link: https://patch.msgid.link/20250306-matt-mctp-i2c-cow-v1-1-293827212681@codeco... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 20b8d7d528baf..fbe8483a07b58 100644 --- a/drivers/net/mctp/mctp-i2c.c +++ b/drivers/net/mctp/mctp-i2c.c @@ -543,6 +543,7 @@ 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; @@ -553,6 +554,10 @@ 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);