1 files changed, 41 insertions, 5 deletions

diff --git a/lib/decompress_unlzo.c b/lib/decompress_unlzo.c
index 855d9d30ec45..7eb3b80bf022 100644
--- a/lib/decompress_unlzo.c
+++ b/lib/decompress_unlzo.c
@@ -48,14 +48,25 @@ static const unsigned char lzop_magic[] = {
 
 #define LZO_BLOCK_SIZE        (256*1024l)
 #define HEADER_HAS_FILTER      0x00000800L
+#define HEADER_SIZE_MIN       (9 + 7     + 4 + 8     + 1       + 4)
+#define HEADER_SIZE_MAX       (9 + 7 + 1 + 8 + 8 + 4 + 1 + 255 + 4)
 
-STATIC inline int INIT parse_header(u8 *input, u8 *skip)
+STATIC inline int INIT parse_header(u8 *input, int *skip, int in_len)
 {
         int l;
         u8 *parse = input;
+        u8 *end = input + in_len;
         u8 level = 0;
         u16 version;
 
+        /*
+         * Check that there's enough input to possibly have a valid header.
+         * Then it is possible to parse several fields until the minimum
+         * size may have been used.
+         */
+        if (in_len < HEADER_SIZE_MIN)
+                return 0;
+
         /* read magic: 9 first bits */
         for (l = 0; l < 9; l++) {
                 if (*parse++ != lzop_magic[l])
@@ -73,6 +84,15 @@ STATIC inline int INIT parse_header(u8 *input, u8 *skip)
         else
                 parse += 4; /* flags */
 
+        /*
+         * At least mode, mtime_low, filename length, and checksum must
+         * be left to be parsed. If also mtime_high is present, it's OK
+         * because the next input buffer check is after reading the
+         * filename length.
+         */
+        if (end - parse < 8 + 1 + 4)
+                return 0;
+
         /* skip mode and mtime_low */
         parse += 8;
         if (version >= 0x0940)
@@ -80,6 +100,8 @@ STATIC inline int INIT parse_header(u8 *input, u8 *skip)
 
         l = *parse++;
         /* don't care about the file name, and skip checksum */
+        if (end - parse < l + 4)
+                return 0;
         parse += l + 4;
 
         *skip = parse - input;
@@ -92,7 +114,8 @@ STATIC inline int INIT unlzo(u8 *input, int in_len,
                                 u8 *output, int *posp,
                                 void (*error) (char *x))
 {
-        u8 skip = 0, r = 0;
+        u8 r = 0;
+        int skip = 0;
         u32 src_len, dst_len;
         size_t tmp;
         u8 *in_buf, *in_buf_save, *out_buf;
@@ -134,19 +157,25 @@ STATIC inline int INIT unlzo(u8 *input, int in_len,
         if (fill)
                 fill(in_buf, lzo1x_worst_compress(LZO_BLOCK_SIZE));
 
-        if (!parse_header(input, &skip)) {
+        if (!parse_header(input, &skip, in_len)) {
                 error("invalid header");
                 goto exit_2;
         }
         in_buf += skip;
+        in_len -= skip;
 
         if (posp)
                 *posp = skip;
 
         for (;;) {
                 /* read uncompressed block size */
+                if (in_len < 4) {
+                        error("file corrupted");
+                        goto exit_2;
+                }
                 dst_len = get_unaligned_be32(in_buf);
                 in_buf += 4;
+                in_len -= 4;
 
                 /* exit if last block */
                 if (dst_len == 0) {
@@ -161,10 +190,15 @@ STATIC inline int INIT unlzo(u8 *input, int in_len,
                 }
 
                 /* read compressed block size, and skip block checksum info */
+                if (in_len < 8) {
+                        error("file corrupted");
+                        goto exit_2;
+                }
                 src_len = get_unaligned_be32(in_buf);
                 in_buf += 8;
+                in_len -= 8;
 
-                if (src_len <= 0 || src_len > dst_len) {
+                if (src_len <= 0 || src_len > dst_len || src_len > in_len) {
                         error("file corrupted");
                         goto exit_2;
                 }
@@ -196,8 +230,10 @@ STATIC inline int INIT unlzo(u8 *input, int in_len,
                 if (fill) {
                         in_buf = in_buf_save;
                         fill(in_buf, lzo1x_worst_compress(LZO_BLOCK_SIZE));
-                } else
+                } else {
                         in_buf += src_len;
+                        in_len -= src_len;
+                }
         }
 
         ret = 0;