From: Alexander Popov <alex.popov@xxxxxxxxx>
commit 23a27722b5292ef0b27403c87a109feea8296a5c upstream.
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@xxxxxxxxx>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
[wsa: use '< 1' instead of '!' for easier readability]
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
[Harshit: backport to 4.14.y, use rdwr_pa[i].len instead of msgs[i].len
as the 4.14.y code uses rdwr_pa.]
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx>
---
Conflicts:
drivers/i2c/i2c-dev.c - use rdwr_pa[i].len instead of
msgs[i].len
Since a NULL pointer dereference happens on 4.14.y this backport patch
will fix the issue.
---
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 b7f9fb00f695..08aff5ebc99a 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -297,7 +297,7 @@ static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
*/
if (rdwr_pa[i].flags & I2C_M_RECV_LEN) {
if (!(rdwr_pa[i].flags & I2C_M_RD) ||
- rdwr_pa[i].buf[0] < 1 ||
+ rdwr_pa[i].len < 1 || rdwr_pa[i].buf[0] < 1 ||
rdwr_pa[i].len < rdwr_pa[i].buf[0] +
I2C_SMBUS_BLOCK_MAX) {
i++;
--
2.37.1
