From: Samanta Navarro Date: Fri, 13 Jan 2023 11:53:41 +0000 (+0000) Subject: mkswap: do not use uninitialized stack value X-Git-Tag: v2.39-rc1~163^2 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=6c88722c175adca5b1a72bcc770f94674405b7f4;p=thirdparty%2Futil-linux.git mkswap: do not use uninitialized stack value If blkdev_get_size fails, then size is not set. Exit with an error code and indicate what went wrong instead of continuing with random stack content. Proof of Concept: ``` $ mkswap /dev/null mkswap: warning: truncating swap area to 17179869180 KiB mkswap: /dev/null: insecure permissions 0666, fix with: chmod 0600 /dev/null mkswap: unable to assign device to libblkid probe ``` The first output line depends on stack content and sometimes does not show up at all. Abort operation if argument is neither regular file nor block device. Signed-off-by: Samanta Navarro --- diff --git a/disk-utils/mkswap.c b/disk-utils/mkswap.c index 7e21647048..bd02301774 100644 --- a/disk-utils/mkswap.c +++ b/disk-utils/mkswap.c @@ -345,8 +345,9 @@ static unsigned long long get_size(const struct mkswap_control *ctl) fd = open(ctl->devname, O_RDONLY); if (fd < 0) err(EXIT_FAILURE, _("cannot open %s"), ctl->devname); - if (blkdev_get_size(fd, &size) == 0) - size /= ctl->pagesize; + if (blkdev_get_size(fd, &size) < 0) + err(EXIT_FAILURE, _("cannot determine size of %s"), ctl->devname); + size /= ctl->pagesize; close(fd); return size;