[PATCH v2] md/raid5: validate payload size before calculating payload_len
From: Martin Wilck <hidden>
Date: 2026-09-02 16:58:14
Also in:
stable
Subsystem:
software raid (multiple disks) support, the rest · Maintainers:
Song Liu, Yu Kuai, Linus Torvalds
Commit b0cc3ae97e89 ("md/raid5: validate payload size before accessing
journal metadata") introduced a bounds check to verify that a given payload
fits into the current metadata block. In order to calculate the payload
size, it has to access the member payload->size, the offset of which may
already be past the end of the metadata block, because the loop condition
only checks that the first byte of the payload is inside, and the payload
entries have variable sizes. Later on, payload->checksum[0] and
payload->checksum[1] are accessed without verifying that payload->size
is large enough.
Add another check to make sure that payload->size can be safely
accessed, and make sure that the checksum fields are accessible.
This issue has been found by AI (gemma4, Gemini) during a backport
review.
Cc: Junrui Luo <redacted>
Cc: stable@vger.kernel.org
Fixes: b0cc3ae97e89 ("md/raid5: validate payload size before accessing journal metadata")
Signed-off-by: Martin Wilck <redacted>
---
Changes v1 -> v2: Fixed issues reported by Sashiko
* fix use of wrong variable name payload_len instead of mb_offset
* add checks to ensure payload->size is large enough to hold the checksum values
---
drivers/md/raid5-cache.c | 30 ++++++++++++++++++++++++------
1 file changed, 24 insertions(+), 6 deletions(-)
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 7b7546bfa21f..4a97846e9030 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c@@ -2002,26 +2002,35 @@ r5l_recovery_verify_data_checksum_for_mb(struct r5l_log *log, return -ENOMEM; while (mb_offset < le32_to_cpu(mb->meta_size)) { + uint32_t payload_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) { + if (mb_offset + sizeof(struct r5l_payload_data_parity) + > le32_to_cpu(mb->meta_size)) + goto mismatch; + payload_size = le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9); 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)) + (sector_t)sizeof(__le32) * payload_size; + if (mb_offset + payload_len > le32_to_cpu(mb->meta_size) || + payload_size < 1) 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) { + if (mb_offset + sizeof(struct r5l_payload_data_parity) + > le32_to_cpu(mb->meta_size)) + goto mismatch; + payload_size = le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9); 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)) + (sector_t)sizeof(__le32) * payload_size; + if (mb_offset + payload_len > le32_to_cpu(mb->meta_size) || + payload_size < conf->max_degraded) goto mismatch; if (r5l_recovery_verify_data_checksum( log, ctx, page, log_offset,
@@ -2035,6 +2044,9 @@ 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) { + if (mb_offset + sizeof(struct r5l_payload_flush) + > le32_to_cpu(mb->meta_size)) + goto mismatch; 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))
@@ -2106,6 +2118,9 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log, if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_FLUSH) { int i, count; + if (mb_offset + sizeof(struct r5l_payload_flush) > + le32_to_cpu(mb->meta_size)) + return -EINVAL; payload_len = sizeof(struct r5l_payload_flush) + (sector_t)le32_to_cpu(payload_flush->size); if (mb_offset + payload_len >
@@ -2130,6 +2145,9 @@ r5c_recovery_analyze_meta_block(struct r5l_log *log, } /* DATA or PARITY payload */ + if (mb_offset + sizeof(struct r5l_payload_data_parity) > + le32_to_cpu(mb->meta_size)) + return -EINVAL; payload_len = sizeof(struct r5l_payload_data_parity) + (sector_t)sizeof(__le32) * (le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
--
2.51.0