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dmg: sanitize chunk length and sectorcount (CVE-2014-0145)

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Chunk length and sectorcount are used for decompression buffers as well
as the bdrv_pread() count argument.  Ensure that they have reasonable
values so neither memory allocation nor conversion from uint64_t to int
will cause problems.

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>
This commit is contained in:
Stefan Hajnoczi 2014-03-26 13:05:58 +01:00
parent eb71803b04
commit c165f77580
1 changed files with 24 additions and 0 deletions
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24
block/dmg.c
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@ -27,6 +27,14 @@
#include "qemu/module.h"
#include <zlib.h>
enum {
/* Limit chunk sizes to prevent unreasonable amounts of memory being used
* or truncating when converting to 32-bit types
*/
DMG_LENGTHS_MAX = 64 * 1024 * 1024, /* 64 MB */
DMG_SECTORCOUNTS_MAX = DMG_LENGTHS_MAX / 512,
};
typedef struct BDRVDMGState {
CoMutex lock;
/* each chunk contains a certain number of sectors,
@ -208,6 +216,14 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
}
offset += 8;
if (s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
error_report("sector count %" PRIu64 " for chunk %u is "
"larger than max (%u)",
s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
ret = -EINVAL;
goto fail;
}
ret = read_uint64(bs, offset, &s->offsets[i]);
if (ret < 0) {
goto fail;
@ -221,6 +237,14 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
}
offset += 8;
if (s->lengths[i] > DMG_LENGTHS_MAX) {
error_report("length %" PRIu64 " for chunk %u is larger "
"than max (%u)",
s->lengths[i], i, DMG_LENGTHS_MAX);
ret = -EINVAL;
goto fail;
}
if (s->lengths[i] > max_compressed_size) {
max_compressed_size = s->lengths[i];
}