From: Tobias Stoeckmann Date: Sun, 28 Aug 2016 19:15:59 +0000 (+0200) Subject: libblkid: Avoid OOB access on illegal ZFS superblocks X-Git-Tag: v2.29-rc1~96 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8fa57ab0b5696031da800e243def32bc5265ff6d;p=thirdparty%2Futil-linux.git libblkid: Avoid OOB access on illegal ZFS superblocks 64 bit systems can trigger an out of boundary access while performing a ZFS superblock probe. This happens due to a possible integer overflow while calculating the remaining available bytes. The variable is of type "int" and the string length is allowed to be larger than INT_MAX, which means that avail calculation can overflow, circumventing the "avail < 0" check and therefore accessing memory outside the "buff" array later on. Signed-off-by: Tobias Stoeckmann --- diff --git a/libblkid/src/superblocks/zfs.c b/libblkid/src/superblocks/zfs.c index b6ffac537b..c41f769905 100644 --- a/libblkid/src/superblocks/zfs.c +++ b/libblkid/src/superblocks/zfs.c @@ -112,7 +112,7 @@ static void zfs_extract_guid_name(blkid_probe pr, loff_t offset) nvs->nvs_type = be32_to_cpu(nvs->nvs_type); nvs->nvs_strlen = be32_to_cpu(nvs->nvs_strlen); - if (nvs->nvs_strlen > UINT_MAX - sizeof(*nvs)) + if (nvs->nvs_strlen > INT_MAX - sizeof(*nvs)) break; avail -= nvs->nvs_strlen + sizeof(*nvs); DBG(LOWPROBE, ul_debug("nvstring: type %u string %*s\n", nvs->nvs_type,