md/raid5: validate payload size before accessing journal metadata

r5c_recovery_analyze_meta_block() and
r5l_recovery_verify_data_checksum_for_mb() iterate over payloads in a
journal metadata block using on-disk payload size fields without
validating them against the remaining space in the metadata block.

A corrupted journal contains payload sizes extending beyond the PAGE_SIZE
boundary can cause out-of-bounds reads when accessing payload fields or
computing offsets.

Add bounds validation for each payload type to ensure the full payload
fits within meta_size before processing.

Fixes: b4c625c ("md/r5cache: r5cache recovery: part 1")
Cc: stable@vger.kernel.org
Signed-off-by: Junrui Luo <moonafterrain@outlook.com>
Link: https://lore.kernel.org/linux-raid/SYBPR01MB78815E78D829BB86CD7C8015AF5FA@SYBPR01MB7881.ausprd01.prod.outlook.com/
Signed-off-by: Yu Kuai <yukuai@fnnas.com>

Author: avasummer

drivers/md/raid5-cache.c

@@ -2002,15 +2002,27 @@ r5l_recovery_verify_data_checksum_for_mb(struct r5l_log *log,
 		return -ENOMEM;
 
 	while (mb_offset < le32_to_cpu(mb->meta_size)) {
+		sector_t payload_len;
+
 		payload = (void *)mb + mb_offset;
 		payload_flush = (void *)mb + mb_offset;
 
 		if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_DATA) {
+			payload_len = sizeof(struct r5l_payload_data_parity) +
+				(sector_t)sizeof(__le32) *
+				(le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
+			if (mb_offset + payload_len > le32_to_cpu(mb->meta_size))
+				goto mismatch;
 			if (r5l_recovery_verify_data_checksum(
 				    log, ctx, page, log_offset,
 				    payload->checksum[0]) < 0)
 				goto mismatch;
 		} else if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_PARITY) {
+			payload_len = sizeof(struct r5l_payload_data_parity) +
+				(sector_t)sizeof(__le32) *
+				(le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
+			if (mb_offset + payload_len > le32_to_cpu(mb->meta_size))
+				goto mismatch;
 			if (r5l_recovery_verify_data_checksum(
 				    log, ctx, page, log_offset,
 				    payload->checksum[0]) < 0)
@@ -2023,22 +2035,18 @@ r5l_recovery_verify_data_checksum_for_mb(struct r5l_log *log,
 				    payload->checksum[1]) < 0)
 				goto mismatch;
 		} else if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_FLUSH) {
-			/* nothing to do for R5LOG_PAYLOAD_FLUSH here */
+			payload_len = sizeof(struct r5l_payload_flush) +
+				(sector_t)le32_to_cpu(payload_flush->size);
+			if (mb_offset + payload_len > le32_to_cpu(mb->meta_size))
+				goto mismatch;
 		} else /* not R5LOG_PAYLOAD_DATA/PARITY/FLUSH */
 			goto mismatch;
 
-		if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_FLUSH) {
-			mb_offset += sizeof(struct r5l_payload_flush) +
-				le32_to_cpu(payload_flush->size);
-		} else {
-			/* DATA or PARITY payload */
+		if (le16_to_cpu(payload->header.type) != R5LOG_PAYLOAD_FLUSH) {
 			log_offset = r5l_ring_add(log, log_offset,
 						  le32_to_cpu(payload->size));
-			mb_offset += sizeof(struct r5l_payload_data_parity) +
-				sizeof(__le32) *
-				(le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
 		}
-
+		mb_offset += payload_len;
 	}
 
 	put_page(page);
@@ -2089,6 +2097,7 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log,
 	log_offset = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);
 
 	while (mb_offset < le32_to_cpu(mb->meta_size)) {
+		sector_t payload_len;
 		int dd;
 
 		payload = (void *)mb + mb_offset;
@@ -2097,6 +2106,12 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log,
 		if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_FLUSH) {
 			int i, count;
 
+			payload_len = sizeof(struct r5l_payload_flush) +
+				(sector_t)le32_to_cpu(payload_flush->size);
+			if (mb_offset + payload_len >
+			    le32_to_cpu(mb->meta_size))
+				return -EINVAL;
+
 			count = le32_to_cpu(payload_flush->size) / sizeof(__le64);
 			for (i = 0; i < count; ++i) {
 				stripe_sect = le64_to_cpu(payload_flush->flush_stripes[i]);
@@ -2110,12 +2125,17 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log,
 				}
 			}
 
-			mb_offset += sizeof(struct r5l_payload_flush) +
-				le32_to_cpu(payload_flush->size);
+			mb_offset += payload_len;
 			continue;
 		}
 
 		/* DATA or PARITY payload */
+		payload_len = sizeof(struct r5l_payload_data_parity) +
+			(sector_t)sizeof(__le32) *
+			(le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
+		if (mb_offset + payload_len > le32_to_cpu(mb->meta_size))
+			return -EINVAL;
+
 		stripe_sect = (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_DATA) ?
 			raid5_compute_sector(
 				conf, le64_to_cpu(payload->location), 0, &dd,
@@ -2180,9 +2200,7 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log,
 		log_offset = r5l_ring_add(log, log_offset,
 					  le32_to_cpu(payload->size));
 
-		mb_offset += sizeof(struct r5l_payload_data_parity) +
-			sizeof(__le32) *
-			(le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
+		mb_offset += payload_len;
 	}
 
 	return 0;