4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Wenwen Wang <wang6495@xxxxxxx> [ Upstream commit 9899e4d3523faaef17c67141aa80ff2088f17871 ] In tw_chrdev_ioctl(), the length of the data buffer is firstly copied from the userspace pointer 'argp' and saved to the kernel object 'data_buffer_length'. Then a security check is performed on it to make sure that the length is not more than 'TW_MAX_IOCTL_SECTORS * 512'. Otherwise, an error code -EINVAL is returned. If the security check is passed, the entire ioctl command is copied again from the 'argp' pointer and saved to the kernel object 'tw_ioctl'. Then, various operations are performed on 'tw_ioctl' according to the 'cmd'. Given that the 'argp' pointer resides in userspace, a malicious userspace process can race to change the buffer length between the two copies. This way, the user can bypass the security check and inject invalid data buffer length. This can cause potential security issues in the following execution. This patch checks for capable(CAP_SYS_ADMIN) in tw_chrdev_open() to avoid the above issues. Signed-off-by: Wenwen Wang <wang6495@xxxxxxx> Acked-by: Adam Radford <aradford@xxxxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/scsi/3w-xxxx.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/scsi/3w-xxxx.c +++ b/drivers/scsi/3w-xxxx.c @@ -1034,6 +1034,9 @@ static int tw_chrdev_open(struct inode * dprintk(KERN_WARNING "3w-xxxx: tw_ioctl_open()\n"); + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + minor_number = iminor(inode); if (minor_number >= tw_device_extension_count) return -ENODEV;
