lzo: properly check for overruns

The lzo decompressor can, if given some really crazy data, possibly
overrun some variable types.  Modify the checking logic to properly
detect overruns before they happen.

Reported-by: "Don A. Bailey" <donb@securitymouse.com>
Tested-by: "Don A. Bailey" <donb@securitymouse.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 41 insertions, 21 deletions

diff --git a/lib/lzo/lzo1x_decompress_safe.c b/lib/lzo/lzo1x_decompress_safe.c
index 569985d522d5..8563081e8da3 100644
--- a/lib/lzo/lzo1x_decompress_safe.c
+++ b/lib/lzo/lzo1x_decompress_safe.c
@@ -19,11 +19,31 @@
 #include <linux/lzo.h>
 #include "lzodefs.h"
 
-#define HAVE_IP(x)      ((size_t)(ip_end - ip) >= (size_t)(x))
-#define HAVE_OP(x)      ((size_t)(op_end - op) >= (size_t)(x))
-#define NEED_IP(x)      if (!HAVE_IP(x)) goto input_overrun
-#define NEED_OP(x)      if (!HAVE_OP(x)) goto output_overrun
-#define TEST_LB(m_pos)  if ((m_pos) < out) goto lookbehind_overrun
+#define HAVE_IP(t, x)                                   \
+        (((size_t)(ip_end - ip) >= (size_t)(t + x)) &&  \
+         (((t + x) >= t) && ((t + x) >= x)))
+
+#define HAVE_OP(t, x)                                   \
+        (((size_t)(op_end - op) >= (size_t)(t + x)) &&  \
+         (((t + x) >= t) && ((t + x) >= x)))
+
+#define NEED_IP(t, x)                                   \
+        do {                                            \
+                if (!HAVE_IP(t, x))                     \
+                        goto input_overrun;             \
+        } while (0)
+
+#define NEED_OP(t, x)                                   \
+        do {                                            \
+                if (!HAVE_OP(t, x))                     \
+                        goto output_overrun;            \
+        } while (0)
+
+#define TEST_LB(m_pos)                                  \
+        do {                                            \
+                if ((m_pos) < out)                      \
+                        goto lookbehind_overrun;        \
+        } while (0)
 
 int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
                           unsigned char *out, size_t *out_len)
@@ -58,14 +78,14 @@ int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
                                         while (unlikely(*ip == 0)) {
                                                 t += 255;
                                                 ip++;
-                                                NEED_IP(1);
+                                                NEED_IP(1, 0);
                                         }
                                         t += 15 + *ip++;
                                 }
                                 t += 3;
 copy_literal_run:
 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
-                                if (likely(HAVE_IP(t + 15) && HAVE_OP(t + 15))) {
+                                if (likely(HAVE_IP(t, 15) && HAVE_OP(t, 15))) {
                                         const unsigned char *ie = ip + t;
                                         unsigned char *oe = op + t;
                                         do {
@@ -81,8 +101,8 @@ copy_literal_run:
                                 } else
 #endif
                                 {
-                                        NEED_OP(t);
-                                        NEED_IP(t + 3);
+                                        NEED_OP(t, 0);
+                                        NEED_IP(t, 3);
                                         do {
                                                 *op++ = *ip++;
                                         } while (--t > 0);
@@ -95,7 +115,7 @@ copy_literal_run:
                                 m_pos -= t >> 2;
                                 m_pos -= *ip++ << 2;
                                 TEST_LB(m_pos);
-                                NEED_OP(2);
+                                NEED_OP(2, 0);
                                 op[0] = m_pos[0];
                                 op[1] = m_pos[1];
                                 op += 2;
@@ -119,10 +139,10 @@ copy_literal_run:
                                 while (unlikely(*ip == 0)) {
                                         t += 255;
                                         ip++;
-                                        NEED_IP(1);
+                                        NEED_IP(1, 0);
                                 }
                                 t += 31 + *ip++;
-                                NEED_IP(2);
+                                NEED_IP(2, 0);
                         }
                         m_pos = op - 1;
                         next = get_unaligned_le16(ip);
@@ -137,10 +157,10 @@ copy_literal_run:
                                 while (unlikely(*ip == 0)) {
                                         t += 255;
                                         ip++;
-                                        NEED_IP(1);
+                                        NEED_IP(1, 0);
                                 }
                                 t += 7 + *ip++;
-                                NEED_IP(2);
+                                NEED_IP(2, 0);
                         }
                         next = get_unaligned_le16(ip);
                         ip += 2;
@@ -154,7 +174,7 @@ copy_literal_run:
 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
                 if (op - m_pos >= 8) {
                         unsigned char *oe = op + t;
-                        if (likely(HAVE_OP(t + 15))) {
+                        if (likely(HAVE_OP(t, 15))) {
                                 do {
                                         COPY8(op, m_pos);
                                         op += 8;
@@ -164,7 +184,7 @@ copy_literal_run:
                                         m_pos += 8;
                                 } while (op < oe);
                                 op = oe;
-                                if (HAVE_IP(6)) {
+                                if (HAVE_IP(6, 0)) {
                                         state = next;
                                         COPY4(op, ip);
                                         op += next;
@@ -172,7 +192,7 @@ copy_literal_run:
                                         continue;
                                 }
                         } else {
-                                NEED_OP(t);
+                                NEED_OP(t, 0);
                                 do {
                                         *op++ = *m_pos++;
                                 } while (op < oe);
@@ -181,7 +201,7 @@ copy_literal_run:
 #endif
                 {
                         unsigned char *oe = op + t;
-                        NEED_OP(t);
+                        NEED_OP(t, 0);
                         op[0] = m_pos[0];
                         op[1] = m_pos[1];
                         op += 2;
@@ -194,15 +214,15 @@ match_next:
                 state = next;
                 t = next;
 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
-                if (likely(HAVE_IP(6) && HAVE_OP(4))) {
+                if (likely(HAVE_IP(6, 0) && HAVE_OP(4, 0))) {
                         COPY4(op, ip);
                         op += t;
                         ip += t;
                 } else
 #endif
                 {
-                        NEED_IP(t + 3);
-                        NEED_OP(t);
+                        NEED_IP(t, 3);
+                        NEED_OP(t, 0);
                         while (t > 0) {
                                 *op++ = *ip++;
                                 t--;