When we allocate the pagetable based on max_table_entries, we multiply the max table entry value by 4 to accomodate a table of 32-bit integers. However, max_table_entries is a uint32_t, and the VPC driver accepts ranges for that entry over 0x40000000. So during this allocation:
s->pagetable = qemu_try_blockalign(bs->file, s->max_table_entries * 4); The size arg overflows, allocating significantly less memory than expected. Since qemu_try_blockalign() size argument is size_t, cast the multiplication correctly to prevent overflow. The value of "max_table_entries * 4" is used elsewhere in the code as well, so store the correct value for use in all those cases. Reported-by: Richard W.M. Jones <rjo...@redhat.com> Signed-off-by: Jeff Cody <jc...@redhat.com> --- block/vpc.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/block/vpc.c b/block/vpc.c index 37572ba..4108b5e 100644 --- a/block/vpc.c +++ b/block/vpc.c @@ -168,6 +168,7 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags, uint8_t buf[HEADER_SIZE]; uint32_t checksum; uint64_t computed_size; + uint64_t pagetable_size; int disk_type = VHD_DYNAMIC; int ret; @@ -269,7 +270,9 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags, goto fail; } - s->pagetable = qemu_try_blockalign(bs->file, s->max_table_entries * 4); + pagetable_size = (size_t) s->max_table_entries * 4; + + s->pagetable = qemu_try_blockalign(bs->file, pagetable_size); if (s->pagetable == NULL) { ret = -ENOMEM; goto fail; @@ -277,14 +280,13 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags, s->bat_offset = be64_to_cpu(dyndisk_header->table_offset); - ret = bdrv_pread(bs->file, s->bat_offset, s->pagetable, - s->max_table_entries * 4); + ret = bdrv_pread(bs->file, s->bat_offset, s->pagetable, pagetable_size); if (ret < 0) { goto fail; } s->free_data_block_offset = - (s->bat_offset + (s->max_table_entries * 4) + 511) & ~511; + (s->bat_offset + pagetable_size + 511) & ~511; for (i = 0; i < s->max_table_entries; i++) { be32_to_cpus(&s->pagetable[i]); -- 1.9.3