File decompress_gunzip-Fix-DoS-if-gzip-is-corrupt.patch of Package busybox.20467

From: Samuel Sapalski <samuel.sapalski@nokia.com>
Date: Wed Mar 3 16:31:22 2021 +0100
Subject: decompress_gunzip: Fix DoS if gzip is corrupt
Patch-mainline: f25d254dfd4243698c31a4f3153d4ac72aa9e9bd
Git-repo: https://git.busybox.net/busybox
Git-commit: be2441a3cdbe98fd64f8ba26c4aa6f022fdf02db
References: 

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>
Signed-off-by: Egbert Eich <eich@suse.de>
---
 archival/libarchive/decompress_gunzip.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/archival/libarchive/decompress_gunzip.c b/archival/libarchive/decompress_gunzip.c
index 4067e1170..14f32c109 100644
--- a/archival/libarchive/decompress_gunzip.c
+++ b/archival/libarchive/decompress_gunzip.c
@@ -221,10 +221,20 @@ 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;
@@ -290,8 +300,6 @@ 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)