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-rw-r--r--lib/decompress_unlzo.c46
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;