diff options
| author | Karl Tomlinson <xmail@karlt.net> | 2013-02-18 01:25:34 +0000 |
|---|---|---|
| committer | Alan Coopersmith <alan.coopersmith@oracle.com> | 2013-03-08 17:31:12 -0800 |
| commit | 39547d600a13713e15429f49768e54c3173c828d (patch) | |
| tree | 03baf8b67729b35ae94542a3898854e3bbb7fd0a | |
| parent | 3cdb6c3a1646f670afa03d424ec12ac418181d1e (diff) | |
MakeBigReq: don't move the last word, already handled by Data32
MakeBigReq inserts a length field after the first 4 bytes of the request
(after req->length), pushing everything else back by 4 bytes.
The current memmove moves everything but the first 4 bytes back.
If a request aligns to the end of the buffer pointer when MakeBigReq is
invoked for that request, this runs over the buffer.
Instead, we need to memmove minus the first 4 bytes (which aren't moved),
minus the last 4 bytes (so we still align to the previous tail).
The 4 bytes that fell out are already handled with Data32, which will
handle the buffermax correctly.
The case where req->length = 1 was already not functional.
Reported by Abhishek Arya <inferno@chromium.org>.
https://bugzilla.mozilla.org/show_bug.cgi?id=803762
Reviewed-by: Jeff Muizelaar <jmuizelaar@mozilla.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Notes
CVE-2013-7439
| -rw-r--r-- | include/X11/Xlibint.h | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/include/X11/Xlibint.h b/include/X11/Xlibint.h index 40965c44..06395b32 100644 --- a/include/X11/Xlibint.h +++ b/include/X11/Xlibint.h @@ -486,6 +486,14 @@ extern void *_XGetRequest(Display *dpy, CARD8 type, size_t len); req = (xReq *) _XGetRequest(dpy, X_/**/name, SIZEOF(xReq)) #endif +/* + * MakeBigReq sets the CARD16 "req->length" to 0 and inserts a new CARD32 + * length, after req->length, before the data in the request. The new length + * includes the "n" extra 32-bit words. + * + * Do not use MakeBigReq if there is no data already in the request. + * req->length must already be >= 2. + */ #ifdef LONG64 #define MakeBigReq(req,n) \ { \ @@ -493,7 +501,7 @@ extern void *_XGetRequest(Display *dpy, CARD8 type, size_t len); CARD32 _BRlen = req->length - 1; \ req->length = 0; \ _BRdat = ((CARD32 *)req)[_BRlen]; \ - memmove(((char *)req) + 8, ((char *)req) + 4, _BRlen << 2); \ + memmove(((char *)req) + 8, ((char *)req) + 4, (_BRlen - 1) << 2); \ ((CARD32 *)req)[1] = _BRlen + n + 2; \ Data32(dpy, &_BRdat, 4); \ } @@ -504,12 +512,19 @@ extern void *_XGetRequest(Display *dpy, CARD8 type, size_t len); CARD32 _BRlen = req->length - 1; \ req->length = 0; \ _BRdat = ((CARD32 *)req)[_BRlen]; \ - memmove(((char *)req) + 8, ((char *)req) + 4, _BRlen << 2); \ + memmove(((char *)req) + 8, ((char *)req) + 4, (_BRlen - 1) << 2); \ ((CARD32 *)req)[1] = _BRlen + n + 2; \ Data32(dpy, &_BRdat, 4); \ } #endif +/* + * SetReqLen increases the count of 32-bit words in the request by "n", + * or by "badlen" if "n" is too large. + * + * Do not use SetReqLen if "req" does not already have data after the + * xReq header. req->length must already be >= 2. + */ #ifndef __clang_analyzer__ #define SetReqLen(req,n,badlen) \ if ((req->length + n) > (unsigned)65535) { \ |