scsi: megaraid_sas: fix a missing-check bug
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>
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@ -7523,6 +7523,9 @@ static int megasas_mgmt_compat_ioctl_fw(struct file *file, unsigned long arg)
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get_user(user_sense_off, &cioc->sense_off))
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return -EFAULT;
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if (local_sense_off != user_sense_off)
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return -EINVAL;
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if (local_sense_len) {
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void __user **sense_ioc_ptr =
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(void __user **)((u8 *)((unsigned long)&ioc->frame.raw) + local_sense_off);
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