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| author | Samuel Sapalski | 2021-03-03 16:31:22 +0100 |
|---|---|---|
| committer | Denys Vlasenko | 2021-05-03 14:50:09 +0200 |
| commit | 23dd1c75b7457f08f1c55a95f3c2fb6faf742562 (patch) | |
| tree | 59c53994c864bd1ca66bd12af247da0f9ef0ab33 | |
| parent | 89358a7131d3e75c74af834bb117b4fad7914983 (diff) | |
| download | busybox-23dd1c75b7457f08f1c55a95f3c2fb6faf742562.zip busybox-23dd1c75b7457f08f1c55a95f3c2fb6faf742562.tar.gz | |
decompress_gunzip: Fix DoS if gzip is corrupt
On certain corrupt gzip files, huft_build will set the error bit on
the result pointer. If afterwards abort_unzip is called huft_free
might run into a segmentation fault or an invalid pointer to
free(p).
In order to mitigate this, we check in huft_free if the error bit
is set and clear it before the linked list is freed.
Signed-off-by: Samuel Sapalski <samuel.sapalski@nokia.com>
Signed-off-by: Peter Kaestle <peter.kaestle@nokia.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
| -rw-r--r-- | archival/libarchive/decompress_gunzip.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/archival/libarchive/decompress_gunzip.c b/archival/libarchive/decompress_gunzip.c index eb3b649..e93cd50 100644 --- a/archival/libarchive/decompress_gunzip.c +++ b/archival/libarchive/decompress_gunzip.c @@ -220,10 +220,20 @@ static const uint8_t border[] ALIGN1 = { * each table. * t: table to free */ +#define BAD_HUFT(p) ((uintptr_t)(p) & 1) +#define ERR_RET ((huft_t*)(uintptr_t)1) static void huft_free(huft_t *p) { huft_t *q; + /* + * If 'p' has the error bit set we have to clear it, otherwise we might run + * into a segmentation fault or an invalid pointer to free(p) + */ + if (BAD_HUFT(p)) { + p = (huft_t*)((uintptr_t)(p) ^ (uintptr_t)(ERR_RET)); + } + /* Go through linked list, freeing from the malloced (t[-1]) address. */ while (p) { q = (--p)->v.t; @@ -289,8 +299,6 @@ static unsigned fill_bitbuffer(STATE_PARAM unsigned bitbuffer, unsigned *current * or a valid pointer to a Huffman table, ORed with 0x1 if incompete table * is given: "fixed inflate" decoder feeds us such data. */ -#define BAD_HUFT(p) ((uintptr_t)(p) & 1) -#define ERR_RET ((huft_t*)(uintptr_t)1) static huft_t* huft_build(const unsigned *b, const unsigned n, const unsigned s, const struct cp_ext *cp_ext, unsigned *m) |