From 7a5022ea64fd6af859383a1731632abc8755b8f7 Mon Sep 17 00:00:00 2001 From: Michael Chang Date: Thu, 26 Aug 2021 15:52:00 +0800 Subject: [PATCH] grub-mkconfig: restore umask for grub.cfg Since 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 grub-mkconfig. The resulting wrong permission (0644) would allow unprivileged users to read grub's 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 set the file mode of creation to 0600 preventing unprivileged access. Fixes: CVE-2021-3981 Signed-off-by: Michael Chang Reviewed-by: Daniel Kiper --- util/grub-mkconfig.in | 2 ++ 1 file changed, 2 insertions(+) diff --git a/util/grub-mkconfig.in b/util/grub-mkconfig.in index 7f6d961d2..4aca09d8e 100644 --- a/util/grub-mkconfig.in +++ b/util/grub-mkconfig.in @@ -351,7 +351,9 @@ 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 # check if default entry need to be corrected for updated distributor version # and/or use fallback entry if default kernel entry removed -- 2.31.1