Commit d65360f2 authored by Chao Yu's avatar Chao Yu Committed by Vlastimil Babka
Browse files

mm/slub: clean up create_unique_id() 

As Christophe JAILLET suggested [1]

In create_unique_id(),

"looks that ID_STR_LENGTH could even be reduced to 32 or 16.

The 2nd BUG_ON at the end of the function could certainly be just
removed as well or remplaced by a:
        if (p > name + ID_STR_LENGTH - 1) {
                kfree(name);
                return -E<something>;
        }
"

According to above suggestion, let's do below cleanups:
1. reduce ID_STR_LENGTH to 32, as the buffer size should be enough;
2. use WARN_ON instead of BUG_ON() and return error if check condition
is true;
3. use snprintf instead of sprintf to avoid overflow.

[1] https://lore.kernel.org/linux-mm/2025305d-16db-abdf-6cd3-1fb93371c2b4@wanadoo.fr/



Suggested-by: default avatarChristophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: default avatarHyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: default avatarChao Yu <chao.yu@oppo.com>
Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
parent 2bfbb027

mm/slub.c

+6 −3
Original line number Diff line number Diff line
@@ -5874,7 +5874,7 @@ static inline struct kset *cache_kset(struct kmem_cache *s) 
	return slab_kset;

}



#define ID_STR_LENGTH 64

#define ID_STR_LENGTH 32



/* Create a unique string id for a slab cache:

 *
@@ -5907,9 +5907,12 @@ static char *create_unique_id(struct kmem_cache *s) 
		*p++ = 'A';

	if (p != name + 1)

		*p++ = '-';

	p += sprintf(p, "%07u", s->size);

	p += snprintf(p, ID_STR_LENGTH - (p - name), "%07u", s->size);



	BUG_ON(p > name + ID_STR_LENGTH - 1);

	if (WARN_ON(p > name + ID_STR_LENGTH - 1)) {

		kfree(name);

		return ERR_PTR(-EINVAL);

	}

	return name;

}