mirror of
https://github.com/openwrt/openwrt.git
synced 2024-12-21 06:33:41 +00:00
71 lines
2.6 KiB
Diff
71 lines
2.6 KiB
Diff
From 237ea0d4762cc14d0fc80e80d61f0f08e1050c7f Mon Sep 17 00:00:00 2001
|
|
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
|
|
Date: Thu, 12 Apr 2018 07:24:52 +0200
|
|
Subject: [PATCH] mtd: bcm47xxpart: improve handling TRX partition size
|
|
MIME-Version: 1.0
|
|
Content-Type: text/plain; charset=UTF-8
|
|
Content-Transfer-Encoding: 8bit
|
|
|
|
When bcm47xxpart finds a TRX partition (container) it's supposed to jump
|
|
to the end of it and keep looking for more partitions. TRX and its
|
|
subpartitions are handled by a separate parser.
|
|
|
|
The problem with old code was relying on the length specified in a TRX
|
|
header. That isn't reliable as TRX is commonly modified to have checksum
|
|
cover only non-changing subpartitions. Otherwise modifying e.g. a rootfs
|
|
would result in CRC32 mismatch and bootloader refusing to boot a
|
|
firmware.
|
|
|
|
Fix it by trying better to figure out a real TRX size. We can securely
|
|
assume that TRX has to cover all subpartitions and the last one is at
|
|
least of a block size in size. Then compare it with a length field.
|
|
|
|
This makes code more optimal & reliable thanks to skipping data that
|
|
shouldn't be parsed.
|
|
|
|
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
|
|
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
|
|
---
|
|
drivers/mtd/bcm47xxpart.c | 22 ++++++++++++++++++----
|
|
1 file changed, 18 insertions(+), 4 deletions(-)
|
|
|
|
--- a/drivers/mtd/bcm47xxpart.c
|
|
+++ b/drivers/mtd/bcm47xxpart.c
|
|
@@ -186,6 +186,8 @@ static int bcm47xxpart_parse(struct mtd_
|
|
/* TRX */
|
|
if (buf[0x000 / 4] == TRX_MAGIC) {
|
|
struct trx_header *trx;
|
|
+ uint32_t last_subpart;
|
|
+ uint32_t trx_size;
|
|
|
|
if (trx_num >= ARRAY_SIZE(trx_parts))
|
|
pr_warn("No enough space to store another TRX found at 0x%X\n",
|
|
@@ -195,11 +197,23 @@ static int bcm47xxpart_parse(struct mtd_
|
|
bcm47xxpart_add_part(&parts[curr_part++], "firmware",
|
|
offset, 0);
|
|
|
|
- /* Jump to the end of TRX */
|
|
+ /*
|
|
+ * Try to find TRX size. The "length" field isn't fully
|
|
+ * reliable as it could be decreased to make CRC32 cover
|
|
+ * only part of TRX data. It's commonly used as checksum
|
|
+ * can't cover e.g. ever-changing rootfs partition.
|
|
+ * Use offsets as helpers for assuming min TRX size.
|
|
+ */
|
|
trx = (struct trx_header *)buf;
|
|
- offset = roundup(offset + trx->length, blocksize);
|
|
- /* Next loop iteration will increase the offset */
|
|
- offset -= blocksize;
|
|
+ last_subpart = max3(trx->offset[0], trx->offset[1],
|
|
+ trx->offset[2]);
|
|
+ trx_size = max(trx->length, last_subpart + blocksize);
|
|
+
|
|
+ /*
|
|
+ * Skip the TRX data. Decrease offset by block size as
|
|
+ * the next loop iteration will increase it.
|
|
+ */
|
|
+ offset += roundup(trx_size, blocksize) - blocksize;
|
|
continue;
|
|
}
|
|
|