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| author | Mike Gabriel <mike.gabriel@das-netzwerkteam.de> | 2015-04-15 10:16:18 +0200 |
|---|---|---|
| committer | Mike Gabriel <mike.gabriel@das-netzwerkteam.de> | 2015-04-15 10:16:18 +0200 |
| commit | 10c40f06e4af9fdb5f34fd09c42c684705662078 (patch) | |
| tree | e3e24fa05b730a364035dc437afd7efc33f9f03b | |
| parent | 65543af56f4f97180b8dda998d5d7101d51ac1a3 (diff) | |
| download | nx-libs-10c40f06e4af9fdb5f34fd09c42c684705662078.tar.gz nx-libs-10c40f06e4af9fdb5f34fd09c42c684705662078.tar.bz2 nx-libs-10c40f06e4af9fdb5f34fd09c42c684705662078.zip | |
MakeBigReq: don't move the last word, already handled by Data32 (X.Org CVE-2013-7439).
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> (against X.Org BTS).
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>
Rebased-for-NX: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>
| -rw-r--r-- | nx-X11/lib/X11/Xlibint.h | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/nx-X11/lib/X11/Xlibint.h b/nx-X11/lib/X11/Xlibint.h index b9a39b25e..b8c0765f2 100644 --- a/nx-X11/lib/X11/Xlibint.h +++ b/nx-X11/lib/X11/Xlibint.h @@ -528,6 +528,14 @@ extern LockInfoPtr _Xglobal_lock; dpy->request++ #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) \ { \ @@ -535,7 +543,7 @@ extern LockInfoPtr _Xglobal_lock; 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); \ } @@ -546,7 +554,7 @@ extern LockInfoPtr _Xglobal_lock; 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); \ } |