From: Randy Dunlap rdunlap@infradead.org
commit e6d094936988910ce6e8197570f2753898830081 upstream.
__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 stack_guard_gap=100", 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 stack_guard_gap=100
Return 1 to indicate that the boot option has been handled.
Note that there is no warning message if someone enters: stack_guard_gap=anything_invalid and 'val' and stack_guard_gap are both set to 0 due to the use of simple_strtoul(). This could be improved by using kstrtoxxx() and checking for an error.
It appears that having stack_guard_gap == 0 is valid (if unexpected) since using "stack_guard_gap=0" on the kernel command line does that.
Link: https://lkml.kernel.org/r/20220222005817.11087-1-rdunlap@infradead.org Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru Fixes: 1be7107fbe18e ("mm: larger stack guard gap, between vmas") Signed-off-by: Randy Dunlap rdunlap@infradead.org Reported-by: Igor Zhbanov i.zhbanov@omprussia.ru Cc: Hugh Dickins hughd@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/mmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/mmap.c +++ b/mm/mmap.c @@ -2551,7 +2551,7 @@ static int __init cmdline_parse_stack_gu if (!*endptr) stack_guard_gap = val << PAGE_SHIFT;
- return 0; + return 1; } __setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);