From 6d3efa68318b33051a7e7a91a6156fba56ec205a Mon Sep 17 00:00:00 2001 From: Sven Hoexter Date: Fri, 30 Oct 2015 10:28:18 +0100 Subject: [PATCH] Add the fix for https://github.com/relan/exfat/issues/6 found and reported by The Fuzzing Project. Detect infinite loop. --- debian/changelog | 2 ++ libexfat/mount.c | 33 +++++++++++++++++++++------------ 2 files changed, 23 insertions(+), 12 deletions(-) diff --git a/debian/changelog b/debian/changelog index 41d33cc..2434953 100644 --- a/debian/changelog +++ b/debian/changelog @@ -2,6 +2,8 @@ exfat-utils (1.1.0-2+deb8u1) UNRELEASED; urgency=medium * Add the fix for https://github.com/relan/exfat/issues/5 found and reported by The Fuzzing Project. Check sector and cluster size. + * Add the fix for https://github.com/relan/exfat/issues/6 found + and reported by The Fuzzing Project. Detect infinite loop. -- diff --git a/libexfat/mount.c b/libexfat/mount.c index 2456187..9a29cbe 100644 --- a/libexfat/mount.c +++ b/libexfat/mount.c @@ -30,23 +30,32 @@ static uint64_t rootdir_size(const struct exfat* ef) { - uint64_t clusters = 0; + uint32_t clusters = 0; + uint32_t clusters_max = le32_to_cpu(ef->sb->cluster_count); cluster_t rootdir_cluster = le32_to_cpu(ef->sb->rootdir_cluster); - while (!CLUSTER_INVALID(rootdir_cluster)) + /* Iterate all clusters of the root directory to calculate its size. + It can't be contiguous because there is no flag to indicate this. */ + do { - clusters++; - /* root directory cannot be contiguous because there is no flag - to indicate this */ + if (clusters == clusters_max) /* infinite loop detected */ + { + exfat_error("root directory cannot occupy all %d clusters", + clusters); + return 0; + } + if (CLUSTER_INVALID(rootdir_cluster)) + { + exfat_error("bad cluster %#x while reading root directory", + rootdir_cluster); + return 0; + } rootdir_cluster = exfat_next_cluster(ef, ef->root, rootdir_cluster); + clusters++; } - if (rootdir_cluster != EXFAT_CLUSTER_END) - { - exfat_error("bad cluster %#x while reading root directory", - rootdir_cluster); - return 0; - } - return clusters * CLUSTER_SIZE(*ef->sb); + while (rootdir_cluster != EXFAT_CLUSTER_END); + + return (uint64_t) clusters * CLUSTER_SIZE(*ef->sb); } static const char* get_option(const char* options, const char* option_name) -- 2.39.5