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| author | Feng Tang <feng.tang@intel.com> | 2022-10-21 06:24:03 +0300 |
|---|---|---|
| committer | Vlastimil Babka <vbabka@suse.cz> | 2022-11-10 18:25:55 +0300 |
| commit | 9ce67395f5a0cdec6ce152d26bfda13b98b25c01 (patch) | |
| tree | 5949b5aa83e3bed842ea147a41d3e10042ac9cca /mm/slub.c | |
| parent | c18c20f16219516b12a4f2fd29c25e06be97e064 (diff) | |
| download | linux-9ce67395f5a0cdec6ce152d26bfda13b98b25c01.tar.xz | |
mm/slub: only zero requested size of buffer for kzalloc when debug enabled
kzalloc/kmalloc will round up the request size to a fixed size
(mostly power of 2), so the allocated memory could be more than
requested. Currently kzalloc family APIs will zero all the
allocated memory.
To detect out-of-bound usage of the extra allocated memory, only
zero the requested part, so that redzone sanity check could be
added to the extra space later.
For kzalloc users who will call ksize() later and utilize this
extra space, please be aware that the space is not zeroed any
more when debug is enabled. (Thanks to Kees Cook's effort to
sanitize all ksize() user cases [1], this won't be a big issue).
[1]. https://lore.kernel.org/all/20220922031013.2150682-1-keescook@chromium.org/#r
Signed-off-by: Feng Tang <feng.tang@intel.com>
Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Diffstat (limited to 'mm/slub.c')
| -rw-r--r-- | mm/slub.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/mm/slub.c b/mm/slub.c index 157527d7101b..ecc44067625c 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3395,7 +3395,11 @@ redo: init = slab_want_init_on_alloc(gfpflags, s); out: - slab_post_alloc_hook(s, objcg, gfpflags, 1, &object, init); + /* + * When init equals 'true', like for kzalloc() family, only + * @orig_size bytes might be zeroed instead of s->object_size + */ + slab_post_alloc_hook(s, objcg, gfpflags, 1, &object, init, orig_size); return object; } @@ -3852,11 +3856,11 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, * Done outside of the IRQ disabled fastpath loop. */ slab_post_alloc_hook(s, objcg, flags, size, p, - slab_want_init_on_alloc(flags, s)); + slab_want_init_on_alloc(flags, s), s->object_size); return i; error: slub_put_cpu_ptr(s->cpu_slab); - slab_post_alloc_hook(s, objcg, flags, i, p, false); + slab_post_alloc_hook(s, objcg, flags, i, p, false, s->object_size); kmem_cache_free_bulk(s, i, p); return 0; } |