mm/page_alloc.c: fix early params garbage value accesses

Previously in '__init early_init_on_alloc' and '__init early_init_on_free'
the return values from 'kstrtobool' were not handled properly.  That
caused potential garbage value read from variable 'bool_result'.
Introduced patch fixes error handling.

Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20200916214125.28271-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cd43e8b..0907884 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -156,16 +156,16 @@ static int __init early_init_on_alloc(char *buf)
        int ret;
        bool bool_result;
 
-       if (!buf)
-               return -EINVAL;
        ret = kstrtobool(buf, &bool_result);
+       if (ret)
+               return ret;
        if (bool_result && page_poisoning_enabled())
                pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, will take precedence over init_on_alloc\n");
        if (bool_result)
                static_branch_enable(&init_on_alloc);
        else
                static_branch_disable(&init_on_alloc);
-       return ret;
+       return 0;
 }
 early_param("init_on_alloc", early_init_on_alloc);
 
@@ -174,16 +174,16 @@ static int __init early_init_on_free(char *buf)
        int ret;
        bool bool_result;
 
-       if (!buf)
-               return -EINVAL;
        ret = kstrtobool(buf, &bool_result);
+       if (ret)
+               return ret;
        if (bool_result && page_poisoning_enabled())
                pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, will take precedence over init_on_free\n");
        if (bool_result)
                static_branch_enable(&init_on_free);
        else
                static_branch_disable(&init_on_free);
-       return ret;
+       return 0;
 }
 early_param("init_on_free", early_init_on_free);