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/openbmc/qemu/tests/qemu-iotests/
H A D075.out509a41ba Wed Mar 26 07:05:26 CDT 2014 Stefan Hajnoczi <stefanha@redhat.com> 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>
H A D075509a41ba Wed Mar 26 07:05:26 CDT 2014 Stefan Hajnoczi <stefanha@redhat.com> 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>
/openbmc/qemu/block/
H A Dcloop.c509a41ba Wed Mar 26 07:05:26 CDT 2014 Stefan Hajnoczi <stefanha@redhat.com> 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>