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From: Jean Delvare <jdelvare@suse.de>
To: Linux I2C <linux-i2c@vger.kernel.org>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
Subject: [PATCH 2/3] i2ctransfer: Prevent msgs[] overflow with many parameters
Date: Tue, 13 May 2025 17:23:30 +0200	[thread overview]
Message-ID: <20250513172330.1b6897d3@endymion> (raw)
In-Reply-To: <20250513172119.09548573@endymion>

There's an off-by-one bug in the message count check to ensure that we
do not process more messages than the kernel allows. nmsgs points to
the index within msgs[] which would be used for the _next_ message. If
this index is equal the maximum number of messages then we must stop
already.

This closes bug #220112:
https://bugzilla.kernel.org/show_bug.cgi?id=220112

Fixes: 9fc53a7fc669 ("i2c-tools: add new tool 'i2ctransfer'")
Signed-off-by: Jean Delvare <jdelvare@suse.de>
---
 tools/i2ctransfer.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- i2c-tools.orig/tools/i2ctransfer.c
+++ i2c-tools/tools/i2ctransfer.c
@@ -193,7 +193,7 @@ int main(int argc, char *argv[])
 		__u8 data, *buf;
 		char *end;
 
-		if (nmsgs > I2C_RDRW_IOCTL_MAX_MSGS) {
+		if (nmsgs == I2C_RDRW_IOCTL_MAX_MSGS) {
 			fprintf(stderr, "Error: Too many messages (max: %d)\n",
 				I2C_RDRW_IOCTL_MAX_MSGS);
 			goto err_out;

-- 
Jean Delvare
SUSE L3 Support

  reply	other threads:[~2025-05-13 15:23 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-05-13 15:21 [PATCH 1/3] i2ctransfer: Don't free memory which was never allocated Jean Delvare
2025-05-13 15:23 ` Jean Delvare [this message]
2025-05-19 15:35   ` [PATCH 2/3] i2ctransfer: Prevent msgs[] overflow with many parameters Wolfram Sang
2025-05-13 15:35 ` [PATCH 3/3] i2ctransfer: Zero out memory passed to ioctl() Jean Delvare
2025-05-19 15:36   ` Wolfram Sang
2025-05-19 15:31 ` [PATCH 1/3] i2ctransfer: Don't free memory which was never allocated Wolfram Sang

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