rpms
/
tigervnc
7
0
Fork 0
Code Issues Pull Requests Releases Activity
tigervnc/SOURCES/tigervnc-be-defensive-about...

356 lines
11 KiB
Diff
Raw Blame History

From 75e6e0653a48baf474fd45d78b1da53e2f324642 Mon Sep 17 00:00:00 2001
From: Pierre Ossman <ossman@cendio.se>
Date: Tue, 24 Sep 2019 09:41:07 +0200
Subject: [PATCH] Be defensive about overflows in stream objects
We use a lot of lengths given to us over the network, so be more
paranoid about them causing an overflow as otherwise an attacker
might trick us in to overwriting other memory.
This primarily affects the client which often gets lengths from the
server, but there are also some scenarios where the server might
theoretically be vulnerable.
Issue found by Pavel Cheremushkin from Kaspersky Lab.
---
common/rdr/FdInStream.cxx | 8 +++++---
common/rdr/FdOutStream.cxx | 7 ++++---
common/rdr/FileInStream.cxx | 8 +++++---
common/rdr/HexInStream.cxx | 8 +++++---
common/rdr/HexOutStream.cxx | 6 ++++--
common/rdr/InStream.h | 24 +++++++++++++-----------
common/rdr/MemOutStream.h | 4 ++++
common/rdr/OutStream.h | 24 +++++++++++++-----------
common/rdr/RandomStream.cxx | 6 ++++--
common/rdr/TLSInStream.cxx | 10 ++++++----
common/rdr/TLSOutStream.cxx | 6 ++++--
common/rdr/ZlibInStream.cxx | 6 ++++--
common/rdr/ZlibOutStream.cxx | 6 ++++--
13 files changed, 75 insertions(+), 48 deletions(-)
diff --git a/common/rdr/FdInStream.cxx b/common/rdr/FdInStream.cxx
index 789cbec..406ece5 100644
--- a/common/rdr/FdInStream.cxx
+++ b/common/rdr/FdInStream.cxx
@@ -136,7 +136,7 @@ size_t FdInStream::overrun(size_t itemSize, size_t nItems, bool wait)
ptr = start;
size_t bytes_to_read;
- while (end < start + itemSize) {
+ while ((size_t)(end - start) < itemSize) {
bytes_to_read = start + bufSize - end;
if (!timing) {
// When not timing, we must be careful not to read too much
@@ -152,8 +152,10 @@ size_t FdInStream::overrun(size_t itemSize, size_t nItems, bool wait)
end += n;
}
- if (itemSize * nItems > (size_t)(end - ptr))
- nItems = (end - ptr) / itemSize;
+ size_t nAvail;
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
return nItems;
}
diff --git a/common/rdr/FdOutStream.cxx b/common/rdr/FdOutStream.cxx
index 1757dc3..f5d07e4 100644
--- a/common/rdr/FdOutStream.cxx
+++ b/common/rdr/FdOutStream.cxx
@@ -149,9 +149,10 @@ size_t FdOutStream::overrun(size_t itemSize, size_t nItems)
}
}
- // Can we fit all the items asked for?
- if (itemSize * nItems > (size_t)(end - ptr))
- nItems = (end - ptr) / itemSize;
+ size_t nAvail;
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
return nItems;
}
diff --git a/common/rdr/FileInStream.cxx b/common/rdr/FileInStream.cxx
index 94f5db8..bdb05a3 100644
--- a/common/rdr/FileInStream.cxx
+++ b/common/rdr/FileInStream.cxx
@@ -68,7 +68,7 @@ size_t FileInStream::overrun(size_t itemSize, size_t nItems, bool wait)
ptr = b;
- while (end < b + itemSize) {
+ while ((size_t)(end - b) < itemSize) {
size_t n = fread((U8 *)end, b + sizeof(b) - end, 1, file);
if (n == 0) {
if (ferror(file))
@@ -80,8 +80,10 @@ size_t FileInStream::overrun(size_t itemSize, size_t nItems, bool wait)
end += b + sizeof(b) - end;
}
- if (itemSize * nItems > (size_t)(end - ptr))
- nItems = (end - ptr) / itemSize;
+ size_t nAvail;
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
return nItems;
}
diff --git a/common/rdr/HexInStream.cxx b/common/rdr/HexInStream.cxx
index 8f93988..a6bc92c 100644
--- a/common/rdr/HexInStream.cxx
+++ b/common/rdr/HexInStream.cxx
@@ -91,7 +91,7 @@ size_t HexInStream::overrun(size_t itemSize, size_t nItems, bool wait) {
offset += ptr - start;
ptr = start;
- while (end < ptr + itemSize) {
+ while ((size_t)(end - ptr) < itemSize) {
size_t n = in_stream.check(2, 1, wait);
if (n == 0) return 0;
const U8* iptr = in_stream.getptr();
@@ -110,8 +110,10 @@ size_t HexInStream::overrun(size_t itemSize, size_t nItems, bool wait) {
end += length;
}
- if (itemSize * nItems > (size_t)(end - ptr))
- nItems = (end - ptr) / itemSize;
+ size_t nAvail;
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
return nItems;
}
diff --git a/common/rdr/HexOutStream.cxx b/common/rdr/HexOutStream.cxx
index 7232514..eac2eff 100644
--- a/common/rdr/HexOutStream.cxx
+++ b/common/rdr/HexOutStream.cxx
@@ -102,8 +102,10 @@ HexOutStream::overrun(size_t itemSize, size_t nItems) {
writeBuffer();
- if (itemSize * nItems > (size_t)(end - ptr))
- nItems = (end - ptr) / itemSize;
+ size_t nAvail;
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
return nItems;
}
diff --git a/common/rdr/InStream.h b/common/rdr/InStream.h
index 14ecf09..f71a4d9 100644
--- a/common/rdr/InStream.h
+++ b/common/rdr/InStream.h
@@ -43,12 +43,15 @@ namespace rdr {
inline size_t check(size_t itemSize, size_t nItems=1, bool wait=true)
{
- if (ptr + itemSize * nItems > end) {
- if (ptr + itemSize > end)
- return overrun(itemSize, nItems, wait);
+ size_t nAvail;
+
+ if (itemSize > (size_t)(end - ptr))
+ return overrun(itemSize, nItems, wait);
+
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
- nItems = (end - ptr) / itemSize;
- }
return nItems;
}
@@ -93,13 +96,12 @@ namespace rdr {
// readBytes() reads an exact number of bytes.
void readBytes(void* data, size_t length) {
- U8* dataPtr = (U8*)data;
- U8* dataEnd = dataPtr + length;
- while (dataPtr < dataEnd) {
- size_t n = check(1, dataEnd - dataPtr);
- memcpy(dataPtr, ptr, n);
+ while (length > 0) {
+ size_t n = check(1, length);
+ memcpy(data, ptr, n);
ptr += n;
- dataPtr += n;
+ data = (U8*)data + n;
+ length -= n;
}
}
diff --git a/common/rdr/MemOutStream.h b/common/rdr/MemOutStream.h
index 4a815b3..b56bac3 100644
--- a/common/rdr/MemOutStream.h
+++ b/common/rdr/MemOutStream.h
@@ -23,6 +23,7 @@
#ifndef __RDR_MEMOUTSTREAM_H__
#define __RDR_MEMOUTSTREAM_H__
+#include <rdr/Exception.h>
#include <rdr/OutStream.h>
namespace rdr {
@@ -65,6 +66,9 @@ namespace rdr {
if (len < (size_t)(end - start) * 2)
len = (end - start) * 2;
+ if (len < (size_t)(end - start))
+ throw Exception("Overflow in MemOutStream::overrun()");
+
U8* newStart = new U8[len];
memcpy(newStart, start, ptr - start);
ptr = newStart + (ptr - start);
diff --git a/common/rdr/OutStream.h b/common/rdr/OutStream.h
index 11aafd2..0f60ccc 100644
--- a/common/rdr/OutStream.h
+++ b/common/rdr/OutStream.h
@@ -46,12 +46,15 @@ namespace rdr {
inline size_t check(size_t itemSize, size_t nItems=1)
{
- if (ptr + itemSize * nItems > end) {
- if (ptr + itemSize > end)
- return overrun(itemSize, nItems);
+ size_t nAvail;
+
+ if (itemSize > (size_t)(end - ptr))
+ return overrun(itemSize, nItems);
+
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
- nItems = (end - ptr) / itemSize;
- }
return nItems;
}
@@ -91,13 +94,12 @@ namespace rdr {
// writeBytes() writes an exact number of bytes.
void writeBytes(const void* data, size_t length) {
- const U8* dataPtr = (const U8*)data;
- const U8* dataEnd = dataPtr + length;
- while (dataPtr < dataEnd) {
- size_t n = check(1, dataEnd - dataPtr);
- memcpy(ptr, dataPtr, n);
+ while (length > 0) {
+ size_t n = check(1, length);
+ memcpy(ptr, data, n);
ptr += n;
- dataPtr += n;
+ data = (U8*)data + n;
+ length -= n;
}
}
diff --git a/common/rdr/RandomStream.cxx b/common/rdr/RandomStream.cxx
index 7681095..6c64ac5 100644
--- a/common/rdr/RandomStream.cxx
+++ b/common/rdr/RandomStream.cxx
@@ -123,8 +123,10 @@ size_t RandomStream::overrun(size_t itemSize, size_t nItems, bool wait) {
*(U8*)end++ = (int) (256.0*rand()/(RAND_MAX+1.0));
}
- if (itemSize * nItems > (size_t)(end - ptr))
- nItems = (end - ptr) / itemSize;
+ size_t nAvail;
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
return nItems;
}
diff --git a/common/rdr/TLSInStream.cxx b/common/rdr/TLSInStream.cxx
index d0f9426..3e1172f 100644
--- a/common/rdr/TLSInStream.cxx
+++ b/common/rdr/TLSInStream.cxx
@@ -43,7 +43,7 @@ ssize_t TLSInStream::pull(gnutls_transport_ptr_t str, void* data, size_t size)
return -1;
}
- if (in->getend() - in->getptr() < (ptrdiff_t)size)
+ if ((size_t)(in->getend() - in->getptr()) < size)
size = in->getend() - in->getptr();
in->readBytes(data, size);
@@ -92,15 +92,17 @@ size_t TLSInStream::overrun(size_t itemSize, size_t nItems, bool wait)
end -= ptr - start;
ptr = start;
- while (end < start + itemSize) {
+ while ((size_t)(end - start) < itemSize) {
size_t n = readTLS((U8*) end, start + bufSize - end, wait);
if (!wait && n == 0)
return 0;
end += n;
}
- if (itemSize * nItems > (size_t)(end - ptr))
- nItems = (end - ptr) / itemSize;
+ size_t nAvail;
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
return nItems;
}
diff --git a/common/rdr/TLSOutStream.cxx b/common/rdr/TLSOutStream.cxx
index 30c456f..7d7c3b5 100644
--- a/common/rdr/TLSOutStream.cxx
+++ b/common/rdr/TLSOutStream.cxx
@@ -100,8 +100,10 @@ size_t TLSOutStream::overrun(size_t itemSize, size_t nItems)
flush();
- if (itemSize * nItems > (size_t)(end - ptr))
- nItems = (end - ptr) / itemSize;
+ size_t nAvail;
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
return nItems;
}
diff --git a/common/rdr/ZlibInStream.cxx b/common/rdr/ZlibInStream.cxx
index e2f971c..9fcfaf6 100644
--- a/common/rdr/ZlibInStream.cxx
+++ b/common/rdr/ZlibInStream.cxx
@@ -113,8 +113,10 @@ size_t ZlibInStream::overrun(size_t itemSize, size_t nItems, bool wait)
return 0;
}
- if (itemSize * nItems > (size_t)(end - ptr))
- nItems = (end - ptr) / itemSize;
+ size_t nAvail;
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
return nItems;
}
diff --git a/common/rdr/ZlibOutStream.cxx b/common/rdr/ZlibOutStream.cxx
index 4e7ffd6..5e158bf 100644
--- a/common/rdr/ZlibOutStream.cxx
+++ b/common/rdr/ZlibOutStream.cxx
@@ -127,8 +127,10 @@ size_t ZlibOutStream::overrun(size_t itemSize, size_t nItems)
}
}
- if (itemSize * nItems > (size_t)(end - ptr))
- nItems = (end - ptr) / itemSize;
+ size_t nAvail;
+ nAvail = (end - ptr) / itemSize;
+ if (nAvail < nItems)
+ return nAvail;
return nItems;
}
Reference in New Issue View Git Blame Copy Permalink