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openSUSE:Maintenance:3335
xorg-x11-server.openSUSE_12.3_Update
U_dbe_unvalidated_lengths_in_DbeSwapBuffers_cal...
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File U_dbe_unvalidated_lengths_in_DbeSwapBuffers_calls.patch of Package xorg-x11-server.openSUSE_12.3_Update
Subject: dbe: unvalidated lengths in DbeSwapBuffers calls References: bnc#907268, CVE-2014-8097 Patch-Mainline: Upstream Signed-off-by: Michal Srb <msrb@suse.com> 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> --- dbe/dbe.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/dbe/dbe.c b/dbe/dbe.c index 527588c..df2ad5c 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; -- 1.7.9.2
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