From 0adec29674561034771c13e446069b41ef41e4d4 Mon Sep 17 00:00:00 2001 From: Michael Chang Date: Fri, 3 Dec 2021 16:13:28 +0800 Subject: [PATCH] grub-mkconfig: Restore umask for the grub.cfg The commit ab2e53c8a (grub-mkconfig: Honor a symlink when generating configuration by grub-mkconfig) has inadvertently discarded umask for creating grub.cfg in the process of running grub-mkconfig. The resulting wrong permission (0644) would allow unprivileged users to read GRUB configuration file content. This presents a low confidentiality risk as grub.cfg may contain non-secured plain-text passwords. This patch restores the missing umask and sets the creation file mode to 0600 preventing unprivileged access. Fixes: CVE-2021-3981 Signed-off-by: Michael Chang Reviewed-by: Daniel Kiper --- util/grub-mkconfig.in | 3 +++ 1 file changed, 3 insertions(+) diff --git a/util/grub-mkconfig.in b/util/grub-mkconfig.in index c3ea7612e..62335d027 100644 --- a/util/grub-mkconfig.in +++ b/util/grub-mkconfig.in @@ -301,7 +301,10 @@ and /etc/grub.d/* files or please file a bug report with exit 1 else # none of the children aborted with error, install the new grub.cfg + oldumask=$(umask) + umask 077 cat ${grub_cfg}.new > ${grub_cfg} + umask $oldumask rm -f ${grub_cfg}.new fi fi -- 2.33.0