4.4-stable review patch. If anyone has any objections, please let me know.
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From: Wenwen Wang wang6495@umn.edu
[ Upstream commit c9318a3e0218bc9dacc25be46b9eec363259536f ]
In twa_chrdev_ioctl(), the ioctl driver command is firstly copied from the userspace pointer 'argp' and saved to the kernel object 'driver_command'. Then a security check is performed on the data buffer size indicated by 'driver_command', which is 'driver_command.buffer_length'. 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 size between the two copies. This way, the user can bypass the security check and inject invalid data buffer size. This can cause potential security issues in the following execution.
This patch checks for capable(CAP_SYS_ADMIN) in twa_chrdev_open()t o avoid the above issues.
Signed-off-by: Wenwen Wang wang6495@umn.edu Acked-by: Adam Radford aradford@gmail.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/scsi/3w-9xxx.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/drivers/scsi/3w-9xxx.c +++ b/drivers/scsi/3w-9xxx.c @@ -889,6 +889,11 @@ static int twa_chrdev_open(struct inode unsigned int minor_number; int retval = TW_IOCTL_ERROR_OS_ENODEV;
+ if (!capable(CAP_SYS_ADMIN)) { + retval = -EACCES; + goto out; + } + minor_number = iminor(inode); if (minor_number >= twa_device_extension_count) goto out;