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block/parallels: Avoid overflows 

Change the types of variables in allocate_clusters() to int64_t so we do
not have to worry about potential overflows.

Add an assertion that our accesses to s->bat[] do not result in a buffer
overflow and that the implicit conversion performed when invoking
bat_entry_off() does not result in an integer overflow.

Coverity-id: 1307776
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20170331170512.10381-1-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2017-03-31 19:05:12 +02:00
parent f82c5b17ea
commit 86d1bd7098
1 changed files with 13 additions and 6 deletions
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19
block/parallels.c
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@ -192,8 +192,7 @@ static int64_t allocate_clusters(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
{
BDRVParallelsState *s = bs->opaque;
uint32_t idx, to_allocate, i;
int64_t pos, space;
int64_t pos, space, idx, to_allocate, i;
pos = block_status(s, sector_num, nb_sectors, pnum);
if (pos > 0) {
@ -201,11 +200,19 @@ static int64_t allocate_clusters(BlockDriverState *bs, int64_t sector_num,
}
idx = sector_num / s->tracks;
if (idx >= s->bat_size) {
return -EINVAL;
}
to_allocate = DIV_ROUND_UP(sector_num + *pnum, s->tracks) - idx;
/* This function is called only by parallels_co_writev(), which will never
* pass a sector_num at or beyond the end of the image (because the block
* layer never passes such a sector_num to that function). Therefore, idx
* is always below s->bat_size.
* block_status() will limit *pnum so that sector_num + *pnum will not
* exceed the image end. Therefore, idx + to_allocate cannot exceed
* s->bat_size.
* Note that s->bat_size is an unsigned int, therefore idx + to_allocate
* will always fit into a uint32_t. */
assert(idx < s->bat_size && idx + to_allocate <= s->bat_size);
space = to_allocate * s->tracks;
if (s->data_end + space > bdrv_getlength(bs->file->bs) >> BDRV_SECTOR_BITS) {
int ret;