From 23a27722b5292ef0b27403c87a109feea8296a5c Mon Sep 17 00:00:00 2001 From: Alexander Popov Date: Thu, 19 Apr 2018 15:29:22 +0300 Subject: i2c: dev: prevent ZERO_SIZE_PTR deref in i2cdev_ioctl_rdwr() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit i2cdev_ioctl_rdwr() allocates i2c_msg.buf using memdup_user(), which returns ZERO_SIZE_PTR if i2c_msg.len is zero. Currently i2cdev_ioctl_rdwr() always dereferences the buf pointer in case of I2C_M_RD | I2C_M_RECV_LEN transfer. That causes a kernel oops in case of zero len. Let's check the len against zero before dereferencing buf pointer. This issue was triggered by syzkaller. Signed-off-by: Alexander Popov Reviewed-by: Uwe Kleine-König [wsa: use '< 1' instead of '!' for easier readability] Signed-off-by: Wolfram Sang --- drivers/i2c/i2c-dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/i2c/i2c-dev.c') diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c index 036a03f0d0a6..1667b6e7674f 100644 --- a/drivers/i2c/i2c-dev.c +++ b/drivers/i2c/i2c-dev.c @@ -280,7 +280,7 @@ static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client, */ if (msgs[i].flags & I2C_M_RECV_LEN) { if (!(msgs[i].flags & I2C_M_RD) || - msgs[i].buf[0] < 1 || + msgs[i].len < 1 || msgs[i].buf[0] < 1 || msgs[i].len < msgs[i].buf[0] + I2C_SMBUS_BLOCK_MAX) { res = -EINVAL; -- cgit v1.2.3