From: Arnd Bergmann <arnd@arndb.de>
Date: Fri, 30 Oct 2020 17:44:20 +0100
Subject: scsi: megaraid_sas: Check user-provided offsets
Git-commit: 381d34e376e3d9d27730fda8a0e870600e6c8196
Patch-mainline: v5.11-rc1
References: bsc#1186535

It sounds unwise to let user space pass an unchecked 32-bit offset into a
kernel structure in an ioctl. This is an unsigned variable, so checking the
upper bound for the size of the structure it points into is sufficient to
avoid data corruption, but as the pointer might also be unaligned, it has
to be written carefully as well.

While I stumbled over this problem by reading the code, I did not continue
checking the function for further problems like it.

Link: https://lore.kernel.org/r/20201030164450.1253641-2-arnd@kernel.org
Fixes: c4a3e0a529ab ("[SCSI] MegaRAID SAS RAID: new driver")
Cc: <stable@vger.kernel.org> # v2.6.15+
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Lee Duncan <lduncan@suse.com>
---
 drivers/scsi/megaraid/megaraid_sas_base.c |   16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -7587,7 +7587,7 @@ megasas_mgmt_fw_ioctl(struct megasas_ins
 	int error = 0, i;
 	void *sense = NULL;
 	dma_addr_t sense_handle;
-	unsigned long *sense_ptr;
+	void *sense_ptr;
 	u32 opcode = 0;
 
 	memset(kbuff_arr, 0, sizeof(kbuff_arr));
@@ -7707,6 +7707,13 @@ megasas_mgmt_fw_ioctl(struct megasas_ins
 	}
 
 	if (ioc->sense_len) {
+		/* make sure the pointer is part of the frame */
+		if (ioc->sense_off >
+		    (sizeof(union megasas_frame) - sizeof(__le64))) {
+			error = -EINVAL;
+			goto out;
+		}
+
 		sense = dma_alloc_coherent(&instance->pdev->dev, ioc->sense_len,
 					     &sense_handle, GFP_KERNEL);
 		if (!sense) {
@@ -7714,12 +7721,11 @@ megasas_mgmt_fw_ioctl(struct megasas_ins
 			goto out;
 		}
 
-		sense_ptr =
-		(unsigned long *) ((unsigned long)cmd->frame + ioc->sense_off);
+		sense_ptr = (void *)cmd->frame + ioc->sense_off;
 		if (instance->consistent_mask_64bit)
-			*sense_ptr = cpu_to_le64(sense_handle);
+			put_unaligned_le64(sense_handle, sense_ptr);
 		else
-			*sense_ptr = cpu_to_le32(sense_handle);
+			put_unaligned_le32(sense_handle, sense_ptr);
 	}
 
 	/*