From 33f5d1a9d9707d1c9ab227aadd9498664e0442e4 Mon Sep 17 00:00:00 2001 From: Matt Johnston Date: Fri, 25 Feb 2022 13:39:38 +0800 Subject: [PATCH] mctp i2c: Fix hard head TX bounds length check We should be testing the length before fitting into the u8 byte_count. This is just a sanity check, the MCTP stack should have limited to MTU which is checked, and we check consistency later in mctp_i2c_xmit(). Found by Smatch mctp_i2c_header_create() warn: impossible condition '(hdr->byte_count > 255) => (0-255 > 255)' Signed-off-by: Matt Johnston Signed-off-by: Jakub Kicinski --- drivers/net/mctp/mctp-i2c.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/mctp/mctp-i2c.c b/drivers/net/mctp/mctp-i2c.c index 470682c88d7e..baf7afac7857 100644 --- a/drivers/net/mctp/mctp-i2c.c +++ b/drivers/net/mctp/mctp-i2c.c @@ -537,6 +537,9 @@ static int mctp_i2c_header_create(struct sk_buff *skb, struct net_device *dev, struct mctp_hdr *mhdr; u8 lldst, llsrc; + if (len > MCTP_I2C_MAXMTU) + return -EMSGSIZE; + lldst = *((u8 *)daddr); llsrc = *((u8 *)saddr); @@ -547,8 +550,6 @@ static int mctp_i2c_header_create(struct sk_buff *skb, struct net_device *dev, hdr->dest_slave = (lldst << 1) & 0xff; hdr->command = MCTP_I2C_COMMANDCODE; hdr->byte_count = len + 1; - if (hdr->byte_count > MCTP_I2C_MAXBLOCK) - return -EMSGSIZE; hdr->source_slave = ((llsrc << 1) & 0xff) | 0x01; mhdr->ver = 0x01;