Commit 86d1bd70 authored by Max Reitz's avatar Max Reitz
Browse files

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: default avatarMax Reitz <mreitz@redhat.com>
Message-id: 20170331170512.10381-1-mreitz@redhat.com
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarPhilippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
parent f82c5b17

block/parallels.c

+13 −6
Original line number Diff line number Diff line
@@ -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;