4.9-stable review patch. If anyone has any objections, please let me know.
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From: Wenwen Wang wang6495@umn.edu
[ Upstream commit 47db7873136a9c57c45390a53b57019cf73c8259 ]
In megasas_mgmt_compat_ioctl_fw(), to handle the structure compat_megasas_iocpacket 'cioc', a user-space structure megasas_iocpacket 'ioc' is allocated before megasas_mgmt_ioctl_fw() is invoked to handle the packet. Since the two data structures have different fields, the data is copied from 'cioc' to 'ioc' field by field. In the copy process, 'sense_ptr' is prepared if the field 'sense_len' is not null, because it will be used in megasas_mgmt_ioctl_fw(). To prepare 'sense_ptr', the user-space data 'ioc->sense_off' and 'cioc->sense_off' are copied and saved to kernel-space variables 'local_sense_off' and 'user_sense_off' respectively. Given that 'ioc->sense_off' is also copied from 'cioc->sense_off', 'local_sense_off' and 'user_sense_off' should have the same value. However, 'cioc' is in the user space and a malicious user can race to change the value of 'cioc->sense_off' after it is copied to 'ioc->sense_off' but before it is copied to 'user_sense_off'. By doing so, the attacker can inject different values into 'local_sense_off' and 'user_sense_off'. This can cause undefined behavior in the following execution, because the two variables are supposed to be same.
This patch enforces a check on the two kernel variables 'local_sense_off' and 'user_sense_off' to make sure they are the same after the copy. In case they are not, an error code EINVAL will be returned.
Signed-off-by: Wenwen Wang wang6495@umn.edu Acked-by: Sumit Saxena sumit.saxena@broadcom.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/scsi/megaraid/megaraid_sas_base.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/scsi/megaraid/megaraid_sas_base.c +++ b/drivers/scsi/megaraid/megaraid_sas_base.c @@ -6901,6 +6901,9 @@ static int megasas_mgmt_compat_ioctl_fw( get_user(user_sense_off, &cioc->sense_off)) return -EFAULT;
+ if (local_sense_off != user_sense_off) + return -EINVAL; + if (local_sense_len) { void __user **sense_ioc_ptr = (void __user **)((u8 *)((unsigned long)&ioc->frame.raw) + local_sense_off);