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qcow1: Validate image size (CVE-2014-0223)

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A huge image size could cause s->l1_size to overflow. Make sure that
images never require a L1 table larger than what fits in s->l1_size.

This cannot only cause unbounded allocations, but also the allocation of
a too small L1 table, resulting in out-of-bounds array accesses (both
reads and writes).

Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2014-05-08 13:08:20 +02:00
parent 42eb58179b
commit 46485de0cb
3 changed files with 30 additions and 2 deletions
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16
block/qcow.c
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@ -61,7 +61,7 @@ typedef struct BDRVQcowState {
int cluster_sectors;
int l2_bits;
int l2_size;
int l1_size;
unsigned int l1_size;
uint64_t cluster_offset_mask;
uint64_t l1_table_offset;
uint64_t *l1_table;
@ -166,7 +166,19 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
/* read the level 1 table */
shift = s->cluster_bits + s->l2_bits;
s->l1_size = (header.size + (1LL << shift) - 1) >> shift;
if (header.size > UINT64_MAX - (1LL << shift)) {
error_setg(errp, "Image too large");
ret = -EINVAL;
goto fail;
} else {
uint64_t l1_size = (header.size + (1LL << shift) - 1) >> shift;
if (l1_size > INT_MAX / sizeof(uint64_t)) {
error_setg(errp, "Image too large");
ret = -EINVAL;
goto fail;
}
s->l1_size = l1_size;
}
s->l1_table_offset = header.l1_table_offset;
s->l1_table = g_malloc(s->l1_size * sizeof(uint64_t));