From 05fe3c103f7e6b8b4fca8a7001dfc9ed4628085b Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Tue, 22 Mar 2022 14:47:52 -0700 Subject: [PATCH] mm/usercopy: return 1 from hardened_usercopy __setup() handler __setup() handlers should return 1 if the command line option is handled and 0 if not (or maybe never return 0; it just pollutes init's environment). This prevents: Unknown kernel command line parameters \ "BOOT_IMAGE=/boot/bzImage-517rc5 hardened_usercopy=off", will be \ passed to user space. Run /sbin/init as init process with arguments: /sbin/init with environment: HOME=/ TERM=linux BOOT_IMAGE=/boot/bzImage-517rc5 hardened_usercopy=off or hardened_usercopy=on but when "hardened_usercopy=foo" is used, there is no Unknown kernel command line parameter. Return 1 to indicate that the boot option has been handled. Print a warning if strtobool() returns an error on the option string, but do not mark this as in unknown command line option and do not cause init's environment to be polluted with this string. Link: https://lkml.kernel.org/r/20220222034249.14795-1-rdunlap@infradead.org Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru Fixes: b5cb15d9372ab ("usercopy: Allow boot cmdline disabling of hardening") Signed-off-by: Randy Dunlap Reported-by: Igor Zhbanov Acked-by: Chris von Recklinghausen Cc: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/usercopy.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/usercopy.c b/mm/usercopy.c index e7b0cb49daa1..bf4d57fefee1 100644 --- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -284,7 +284,10 @@ static bool enable_checks __initdata = true; static int __init parse_hardened_usercopy(char *str) { - return strtobool(str, &enable_checks); + if (strtobool(str, &enable_checks)) + pr_warn("Invalid option string for hardened_usercopy: '%s'\n", + str); + return 1; } __setup("hardened_usercopy=", parse_hardened_usercopy); -- GitLab