[PATCH] bunzip2: fix rare decompression failure

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

The decompression code parses a huffman tree and counts the number of
symbols for a given bit length.  In rare cases, there may be >= 256
symbols with a given bit length, causing the unsigned char to overflow.
This causes a decompression failure later when the code tries and fails to
find the bit length for a given symbol.

Since the maximum number of symbols is 258, use unsigned short instead.

Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---

This issue was noticed in Linux decompressing initrds but since Xen has
the same decompression code, it is possible the issue occurs here too.

 xen/common/bunzip2.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/xen/common/bunzip2.c b/xen/common/bunzip2.c
index 4466426941e0..79f17162b138 100644
--- a/xen/common/bunzip2.c
+++ b/xen/common/bunzip2.c
@@ -221,7 +221,8 @@ static int __init get_next_block(struct bunzip_data *bd)
           RUNB) */
        symCount = symTotal+2;
        for (j = 0; j < groupCount; j++) {
-               unsigned char length[MAX_SYMBOLS], temp[MAX_HUFCODE_BITS+1];
+               unsigned char length[MAX_SYMBOLS];
+               unsigned short temp[MAX_HUFCODE_BITS+1];
                int     minLen, maxLen, pp;
                /* Read Huffman code lengths for each symbol.  They're
                   stored in a way similar to mtf; record a starting
-- 
2.45.2