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author | Max Reitz <mreitz@redhat.com> | 2017-03-31 19:05:12 +0200 |
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committer | Max Reitz <mreitz@redhat.com> | 2017-04-03 17:11:40 +0200 |
commit | 86d1bd70987cd11d85d01f52aa5824c63d910471 (patch) | |
tree | e103c4b121c6b1d25c3b60cacb55ac3c2783697d /block | |
parent | f82c5b17ea85d8f432069a4afd6cbdb65d9d8a66 (diff) | |
download | qemu-86d1bd70987cd11d85d01f52aa5824c63d910471.zip qemu-86d1bd70987cd11d85d01f52aa5824c63d910471.tar.gz qemu-86d1bd70987cd11d85d01f52aa5824c63d910471.tar.bz2 |
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>
Diffstat (limited to 'block')
-rw-r--r-- | block/parallels.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/block/parallels.c b/block/parallels.c index 4173b3f..90acf79 100644 --- a/block/parallels.c +++ b/block/parallels.c @@ -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; |