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author | Stefan Hajnoczi <stefanha@redhat.com> | 2014-03-26 13:05:26 +0100 |
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committer | Stefan Hajnoczi <stefanha@redhat.com> | 2014-04-01 13:59:47 +0200 |
commit | 509a41bab5306181044b5fff02eadf96d9c8676a (patch) | |
tree | d539979df142d4d46cfc0137032d0098fc973dc8 /block | |
parent | d65f97a82c4ed48374a764c769d4ba1ea9724e97 (diff) | |
download | qemu-509a41bab5306181044b5fff02eadf96d9c8676a.zip qemu-509a41bab5306181044b5fff02eadf96d9c8676a.tar.gz qemu-509a41bab5306181044b5fff02eadf96d9c8676a.tar.bz2 |
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')
-rw-r--r-- | block/cloop.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/block/cloop.c b/block/cloop.c index f021663..563e916 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); |