From 06a3241c27c6550e3cba39c69035da8e984bf41a Mon Sep 17 00:00:00 2001 From: rmilecki Date: Mon, 9 May 2016 12:53:39 +0000 Subject: [PATCH] mtd: seama: fix image data handling MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 1) Put sanity checks in one place 2) Respect provided offset 3) Read only as much data as needed for MD5 calculation Thanks to the last change this is a great speedup and memory saver. On devices with NAND flash we were allocating & reading about 128 MiB while something about 8 MiB is enough. Signed-off-by: Rafał Miłecki --- package/system/mtd/src/seama.c | 46 +++++++++++++--------------------- 1 file changed, 18 insertions(+), 28 deletions(-) diff --git a/package/system/mtd/src/seama.c b/package/system/mtd/src/seama.c index dac5da2b85..e3c0e4d51e 100644 --- a/package/system/mtd/src/seama.c +++ b/package/system/mtd/src/seama.c @@ -51,49 +51,30 @@ ssize_t pread(int fd, void *buf, size_t count, off_t offset); ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset); int -seama_fix_md5(struct seama_entity_header *shdr, int fd, size_t len, size_t block_offset) +seama_fix_md5(struct seama_entity_header *shdr, int fd, size_t data_offset, size_t data_size) { char *buf; - char *data; ssize_t res; - size_t msize; - size_t isize; MD5_CTX ctx; unsigned char digest[16]; int i; int err = 0; - if (len < sizeof(struct seama_entity_header)) - return -1; - - buf = malloc(len); + buf = malloc(data_size); if (!buf) { err = -ENOMEM; goto err_out; } - res = pread(fd, buf, len, block_offset); - if (res != len) { + res = pread(fd, buf, data_size, data_offset); + if (res != data_size) { perror("pread"); err = -EIO; goto err_free; } - isize = ntohl(shdr->size); - msize = ntohs(shdr->metasize); - if (isize == 0) { - /* the image contains no checksum */ - return -1; - } - - len -= sizeof(struct seama_entity_header) + msize; - if (isize > len) - isize = len; - - data = buf + sizeof(struct seama_entity_header) + msize; - MD5_Init(&ctx); - MD5_Update(&ctx, data, isize); + MD5_Update(&ctx, buf, data_size); MD5_Final(digest, &ctx); if (!memcmp(digest, shdr->md5, sizeof(digest))) { @@ -103,7 +84,7 @@ seama_fix_md5(struct seama_entity_header *shdr, int fd, size_t len, size_t block } if (quiet < 2) { - fprintf(stderr, "new size:%u, new MD5: ", isize); + fprintf(stderr, "new size:%u, new MD5: ", data_size); for (i = 0; i < sizeof(digest); i++) fprintf(stderr, "%02x", digest[i]); @@ -111,7 +92,7 @@ seama_fix_md5(struct seama_entity_header *shdr, int fd, size_t len, size_t block } /* update the size in the image */ - shdr->size = htonl(isize); + shdr->size = htonl(data_size); /* update the checksum in the image */ memcpy(shdr->md5, digest, sizeof(digest)); @@ -129,6 +110,8 @@ mtd_fixseama(const char *mtd, size_t offset) char *first_block; ssize_t res; size_t block_offset; + size_t data_offset; + size_t data_size; struct seama_entity_header *shdr; if (quiet < 2) @@ -162,13 +145,20 @@ mtd_fixseama(const char *mtd, size_t offset) exit(1); } - shdr = (struct seama_entity_header *)first_block; + shdr = (struct seama_entity_header *)(first_block + offset); if (shdr->magic != htonl(SEAMA_MAGIC)) { fprintf(stderr, "No SEAMA header found\n"); return -1; + } else if (!ntohl(shdr->size)) { + fprintf(stderr, "Seama entity with empty image\n"); + exit(1); } - if (seama_fix_md5(shdr, fd, mtdsize, block_offset)) + data_offset = offset + sizeof(struct seama_entity_header) + ntohs(shdr->metasize); + data_size = mtdsize - data_offset; + if (data_size > ntohl(shdr->size)) + data_size = ntohl(shdr->size); + if (seama_fix_md5(shdr, fd, data_offset, data_size)) goto out; if (mtd_erase_block(fd, block_offset)) { -- 2.25.1