Commit 33f5d1a9 authored by Matt Johnston's avatar Matt Johnston Committed by Jakub Kicinski
Browse files

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: default avatarMatt Johnston <matt@codeconstruct.com.au>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 06bf1ce6

drivers/net/mctp/mctp-i2c.c

+3 −2
Original line number Diff line number Diff line
@@ -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;