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Avoid to read blocks from start of CE area which do not belong to the given file

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This commit is contained in:
Thomas Schmitt 2017-08-19 14:54:23 +02:00
parent 91490d5f34
commit 31088d9acc
1 changed files with 15 additions and 7 deletions
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22
libisofs/rockridge_read.c
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@ -67,6 +67,10 @@ susp_iter_new(IsoDataSource *src, struct ecma119_dir_record *record,
return iter; return iter;
} }
/* More than 1 MiB in a single file's CE area is suspicious */
#define ISO_SUSP_MAX_CE_BYTES (1024 * 1024)
/* @param flag bit0 = First call on root: /* @param flag bit0 = First call on root:
Not yet clear whether this is SUSP at all Not yet clear whether this is SUSP at all
*/ */
@ -95,24 +99,28 @@ int susp_iter_next(SuspIterator *iter, struct susp_sys_user_entry **sue,
* (IEEE 1281, SUSP. section 4) * (IEEE 1281, SUSP. section 4)
*/ */
if (iter->ce_len) { if (iter->ce_len) {
uint32_t block, nblocks; uint32_t block, nblocks, skipped_blocks, skipped_bytes;
/* A CE was found, there is another continuation area */ /* A CE was found, there is another continuation area */
nblocks = DIV_UP(iter->ce_off + iter->ce_len, BLOCK_SIZE); skipped_blocks = iter->ce_off / BLOCK_SIZE;
if (nblocks <= 0) skipped_bytes = skipped_blocks * BLOCK_SIZE;
nblocks = DIV_UP(iter->ce_off - skipped_bytes + iter->ce_len,
BLOCK_SIZE);
if (nblocks <= 0 || iter->ce_len > ISO_SUSP_MAX_CE_BYTES)
return ISO_SUSP_WRONG_CE_SIZE; return ISO_SUSP_WRONG_CE_SIZE;
iter->buffer = realloc(iter->buffer, nblocks * BLOCK_SIZE); iter->buffer = realloc(iter->buffer, nblocks * BLOCK_SIZE);
/* read all blocks needed to cache the full CE */ /* Read blocks needed to cache the given CE area range */
for (block = 0; block < nblocks; ++block) { for (block = 0; block < nblocks; ++block) {
int ret; int ret;
ret = iter->src->read_block(iter->src, iter->ce_block + block, ret = iter->src->read_block(iter->src,
iter->buffer + block * BLOCK_SIZE); iter->ce_block + skipped_blocks + block,
iter->buffer + block * BLOCK_SIZE);
if (ret < 0) { if (ret < 0) {
return ret; return ret;
} }
} }
iter->base = iter->buffer + iter->ce_off; iter->base = iter->buffer + (iter->ce_off - skipped_bytes);
iter->pos = 0; iter->pos = 0;
iter->size = iter->ce_len; iter->size = iter->ce_len;
iter->ce_len = 0; iter->ce_len = 0;