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authorAlan Coopersmith <alan.coopersmith@oracle.com>2014-01-22 23:12:04 -0800
committerAlan Coopersmith <alan.coopersmith@oracle.com>2014-12-08 18:09:48 -0800
commit2ef42519c41e793579c9cea699c866fee3d9321f (patch)
treed94097650387d63dc7fd3170c96ab910cb5d1de4 /dbe
parent6692670fde081bbfe9313f17d84037ae9116702a (diff)
dbe: unvalidated lengths in DbeSwapBuffers calls [CVE-2014-8097]
ProcDbeSwapBuffers() has a 32bit (n) length value that it uses to read from a buffer. The length is never validated, which can lead to out of bound reads, and possibly returning the data read from out of bounds to the misbehaving client via an X Error packet. SProcDbeSwapBuffers() swaps data (for correct endianness) before handing it off to the real proc. While doing the swapping, the length field is not validated, which can cause memory corruption. v2: reorder checks to avoid compilers optimizing out checks for overflow that happen after we'd already have done the overflowing multiplications. Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com> Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com> Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Diffstat (limited to 'dbe')
-rw-r--r--dbe/dbe.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/dbe/dbe.c b/dbe/dbe.c
index 527588c3c..df2ad5c51 100644
--- a/dbe/dbe.c
+++ b/dbe/dbe.c
@@ -450,18 +450,20 @@ ProcDbeSwapBuffers(ClientPtr client)
DbeSwapInfoPtr swapInfo;
xDbeSwapInfo *dbeSwapInfo;
int error;
- register int i, j;
- int nStuff;
+ unsigned int i, j;
+ unsigned int nStuff;
REQUEST_AT_LEAST_SIZE(xDbeSwapBuffersReq);
nStuff = stuff->n; /* use local variable for performance. */
if (nStuff == 0) {
+ REQUEST_SIZE_MATCH(xDbeSwapBuffersReq);
return Success;
}
if (nStuff > UINT32_MAX / sizeof(DbeSwapInfoRec))
return BadAlloc;
+ REQUEST_FIXED_SIZE(xDbeSwapBuffersReq, nStuff * sizeof(xDbeSwapInfo));
/* Get to the swap info appended to the end of the request. */
dbeSwapInfo = (xDbeSwapInfo *) &stuff[1];
@@ -914,13 +916,16 @@ static int
SProcDbeSwapBuffers(ClientPtr client)
{
REQUEST(xDbeSwapBuffersReq);
- register int i;
+ unsigned int i;
xDbeSwapInfo *pSwapInfo;
swaps(&stuff->length);
REQUEST_AT_LEAST_SIZE(xDbeSwapBuffersReq);
swapl(&stuff->n);
+ if (stuff->n > UINT32_MAX / sizeof(DbeSwapInfoRec))
+ return BadAlloc;
+ REQUEST_FIXED_SIZE(xDbeSwapBuffersReq, stuff->n * sizeof(xDbeSwapInfo));
if (stuff->n != 0) {
pSwapInfo = (xDbeSwapInfo *) stuff + 1;