mtd: bcm47xxpart: improve handling TRX partition size
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>
This commit is contained in:
parent
5ac67ce36c
commit
237ea0d476
|
@ -186,6 +186,8 @@ static int bcm47xxpart_parse(struct mtd_info *master,
|
||||||
/* TRX */
|
/* TRX */
|
||||||
if (buf[0x000 / 4] == TRX_MAGIC) {
|
if (buf[0x000 / 4] == TRX_MAGIC) {
|
||||||
struct trx_header *trx;
|
struct trx_header *trx;
|
||||||
|
uint32_t last_subpart;
|
||||||
|
uint32_t trx_size;
|
||||||
|
|
||||||
if (trx_num >= ARRAY_SIZE(trx_parts))
|
if (trx_num >= ARRAY_SIZE(trx_parts))
|
||||||
pr_warn("No enough space to store another TRX found at 0x%X\n",
|
pr_warn("No enough space to store another TRX found at 0x%X\n",
|
||||||
|
@ -195,11 +197,23 @@ static int bcm47xxpart_parse(struct mtd_info *master,
|
||||||
bcm47xxpart_add_part(&parts[curr_part++], "firmware",
|
bcm47xxpart_add_part(&parts[curr_part++], "firmware",
|
||||||
offset, 0);
|
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;
|
trx = (struct trx_header *)buf;
|
||||||
offset = roundup(offset + trx->length, blocksize);
|
last_subpart = max3(trx->offset[0], trx->offset[1],
|
||||||
/* Next loop iteration will increase the offset */
|
trx->offset[2]);
|
||||||
offset -= blocksize;
|
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;
|
continue;
|
||||||
}
|
}
|
||||||
|
|
||||||
|
|
Loading…
Reference in a new issue