This is a note to let you know that I've just added the patch titled i2c: dev: prevent ZERO_SIZE_PTR deref in i2cdev_ioctl_rdwr() to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: i2c-dev-prevent-zero_size_ptr-deref-in-i2cdev_ioctl_rdwr.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 23a27722b5292ef0b27403c87a109feea8296a5c Mon Sep 17 00:00:00 2001 From: Alexander Popov <alex.popov@xxxxxxxxx> 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 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> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/i2c/i2c-dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/i2c/i2c-dev.c +++ b/drivers/i2c/i2c-dev.c @@ -297,7 +297,7 @@ static noinline int i2cdev_ioctl_rdwr(st */ 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++; Patches currently in stable-queue which might be from alex.popov@xxxxxxxxx are queue-4.14/i2c-dev-prevent-zero_size_ptr-deref-in-i2cdev_ioctl_rdwr.patch