linux-kernel - [PATCH v2] i2c: don't pass 0 nmsgs to i2c

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Date:   Sat, 25 Dec 2021 21:24:18 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     wsa@...nel.org, viro@...iv.linux.org.uk
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pavel Skripkin <paskripkin@...il.com>,
        syzbot+e417648b303855b91d8a@...kaller.appspotmail.com
Subject: [PATCH v2] i2c: don't pass 0 nmsgs to i2c_transfer

We should not pass 0 nmsgs to i2c_transfer(), since it will cause
warning. This patch adds missing validation check to prevent passing
0 nmsgs to i2c_transfer().

Reported-and-tested-by: syzbot+e417648b303855b91d8a@...kaller.appspotmail.com
Fixes: 7d5cb45655f2 ("i2c compat ioctls: move to ->compat_ioctl()")
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
---

Changes in v2:
	- Fixed typos in commit message

---
 drivers/i2c/i2c-dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index bce0e8bb7852..3b54efa4b1ec 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -535,7 +535,7 @@ static long compat_i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned lo
 				   sizeof(rdwr_arg)))
 			return -EFAULT;
 
-		if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
+		if (!rdwr_arg.nmsgs || rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
 			return -EINVAL;
 
 		rdwr_pa = kmalloc_array(rdwr_arg.nmsgs, sizeof(struct i2c_msg),
-- 
2.34.1