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authorAlexander Popov <alex.popov@linux.com>2018-04-19 15:29:22 +0300
committerWolfram Sang <wsa@the-dreams.de>2018-04-27 14:04:10 +0200
commit23a27722b5292ef0b27403c87a109feea8296a5c (patch)
tree3516ceaf2c36581588bcb11db81b669f4e45bba3 /drivers/i2c/i2c-dev.c
parent40d802cb66ad110673e40cb3426b1f1c79645104 (diff)
downloadlinux-23a27722b5292ef0b27403c87a109feea8296a5c.tar.bz2
i2c: dev: prevent ZERO_SIZE_PTR deref in i2cdev_ioctl_rdwr()
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 <alex.popov@linux.com> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> [wsa: use '< 1' instead of '!' for easier readability] Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c/i2c-dev.c')
-rw-r--r--drivers/i2c/i2c-dev.c2
1 files changed, 1 insertions, 1 deletions
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;