From d9a832a2edbf95d664b07791f77a22ac3dfb95f5 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= Date: Thu, 10 Jan 2019 12:11:04 +0100 Subject: [PATCH] Fix CVE-2018-15127 (Heap out-of-bounds write in rfbserver.c:rfbProcessFileTransferReadBuffer()) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This patch contains the following three upstream patches squashed together and ported to 0.9.11 version: commit 502821828ed00b4a2c4bef90683d0fd88ce495de Author: Christian Beier Date: Sun Oct 21 20:21:30 2018 +0200 LibVNCServer: fix heap out-of-bound write access Closes #243 commit 15bb719c03cc70f14c36a843dcb16ed69b405707 Author: Christian Beier Date: Sun Jan 6 15:13:56 2019 +0100 Error out in rfbProcessFileTransferReadBuffer if length can not be allocated re #273 commit 09e8fc02f59f16e2583b34fe1a270c238bd9ffec Author: Petr Písař Date: Mon Jan 7 10:40:01 2019 +0100 Limit lenght to INT_MAX bytes in rfbProcessFileTransferReadBuffer() This ammends 15bb719c03cc70f14c36a843dcb16ed69b405707 fix for a heap out-of-bound write access in rfbProcessFileTransferReadBuffer() when reading a transfered file content in a server. The former fix did not work on platforms with a 32-bit int type (expected by rfbReadExact()). CVE-2018-15127 Signed-off-by: Petr Písař --- libvncserver/rfbserver.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/libvncserver/rfbserver.c b/libvncserver/rfbserver.c index b50a7f4..1b4dd97 100644 --- a/libvncserver/rfbserver.c +++ b/libvncserver/rfbserver.c @@ -1471,11 +1471,24 @@ char *rfbProcessFileTransferReadBuffer(rfbClientPtr cl, uint32_t length) int n=0; FILEXFER_ALLOWED_OR_CLOSE_AND_RETURN("", cl, NULL); + /* - rfbLog("rfbProcessFileTransferReadBuffer(%dlen)\n", length); + We later alloc length+1, which might wrap around on 32-bit systems if length equals + 0XFFFFFFFF, i.e. SIZE_MAX for 32-bit systems. On 64-bit systems, a length of 0XFFFFFFFF + will safely be allocated since this check will never trigger and malloc() can digest length+1 + without problems as length is a uint32_t. + We also later pass length to rfbReadExact() that expects a signed int type and + that might wrap on platforms with a 32-bit int type if length is bigger + than 0X7FFFFFFF. */ + if(length == SIZE_MAX || length > INT_MAX) { + rfbErr("rfbProcessFileTransferReadBuffer: too big file transfer length requested: %u", (unsigned int)length); + rfbCloseClient(cl); + return NULL; + } + if (length>0) { - buffer=malloc(length+1); + buffer=malloc((size_t)length+1); if (buffer!=NULL) { if ((n = rfbReadExact(cl, (char *)buffer, length)) <= 0) { if (n != 0) -- 2.17.2