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authorStefan Hajnoczi <stefanha@redhat.com>2014-03-26 13:05:26 +0100
committerStefan Hajnoczi <stefanha@redhat.com>2014-04-01 13:59:47 +0200
commit509a41bab5306181044b5fff02eadf96d9c8676a (patch)
treed539979df142d4d46cfc0137032d0098fc973dc8 /block/cloop.c
parentd65f97a82c4ed48374a764c769d4ba1ea9724e97 (diff)
block/cloop: prevent offsets_size integer overflow (CVE-2014-0143)
The following integer overflow in offsets_size can lead to out-of-bounds memory stores when n_blocks has a huge value: uint32_t n_blocks, offsets_size; [...] ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4); [...] s->n_blocks = be32_to_cpu(s->n_blocks); /* read offsets */ offsets_size = s->n_blocks * sizeof(uint64_t); s->offsets = g_malloc(offsets_size); [...] for(i=0;i<s->n_blocks;i++) { s->offsets[i] = be64_to_cpu(s->offsets[i]); offsets_size can be smaller than n_blocks due to integer overflow. Therefore s->offsets[] is too small when the for loop byteswaps offsets. This patch refuses to open files if offsets_size would overflow. Note that changing the type of offsets_size is not a fix since 32-bit hosts still only have 32-bit size_t. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block/cloop.c')
-rw-r--r--block/cloop.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/block/cloop.c b/block/cloop.c
index f0216637e1..563e916266 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -99,6 +99,13 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
s->n_blocks = be32_to_cpu(s->n_blocks);
/* read offsets */
+ if (s->n_blocks > UINT32_MAX / sizeof(uint64_t)) {
+ /* Prevent integer overflow */
+ error_setg(errp, "n_blocks %u must be %zu or less",
+ s->n_blocks,
+ UINT32_MAX / sizeof(uint64_t));
+ return -EINVAL;
+ }
offsets_size = s->n_blocks * sizeof(uint64_t);
s->offsets = g_malloc(offsets_size);