diff options
| author | Len Baker <len.baker@gmx.com> | 2021-11-05 13:37:40 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-11-06 13:30:35 -0700 |
| commit | 16f6bf266c94017c2c4699acab64316ddc0ee77c (patch) | |
| tree | c64f7b6e76c01a1b91d866f45622c629f1e14a0b | |
| parent | 38d4ef44ee4a7dbdf220daa52ad341c140f3bb51 (diff) | |
mm/list_lru.c: prefer struct_size over open coded arithmetic
As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing.
This could lead to values wrapping around and a smaller allocation being
made than the caller was expecting. Using those allocations could lead
to linear overflows of heap memory and other misbehaviors.
So, use the struct_size() helper to do the arithmetic instead of the
argument "size + count * size" in the kvmalloc() functions.
Also, take the opportunity to refactor the memcpy() call to use the
flex_array_size() helper.
This code was detected with the help of Coccinelle and audited and fixed
manually.
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
Link: https://lkml.kernel.org/r/20211017105929.9284-1-len.baker@gmx.com
Signed-off-by: Len Baker <len.baker@gmx.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/list_lru.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/mm/list_lru.c b/mm/list_lru.c index cd58790d0fb3..a6031f1c5bd7 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -354,8 +354,7 @@ static int memcg_init_list_lru_node(struct list_lru_node *nlru) struct list_lru_memcg *memcg_lrus; int size = memcg_nr_cache_ids; - memcg_lrus = kvmalloc(sizeof(*memcg_lrus) + - size * sizeof(void *), GFP_KERNEL); + memcg_lrus = kvmalloc(struct_size(memcg_lrus, lru, size), GFP_KERNEL); if (!memcg_lrus) return -ENOMEM; @@ -389,7 +388,7 @@ static int memcg_update_list_lru_node(struct list_lru_node *nlru, old = rcu_dereference_protected(nlru->memcg_lrus, lockdep_is_held(&list_lrus_mutex)); - new = kvmalloc(sizeof(*new) + new_size * sizeof(void *), GFP_KERNEL); + new = kvmalloc(struct_size(new, lru, new_size), GFP_KERNEL); if (!new) return -ENOMEM; @@ -398,7 +397,7 @@ static int memcg_update_list_lru_node(struct list_lru_node *nlru, return -ENOMEM; } - memcpy(&new->lru, &old->lru, old_size * sizeof(void *)); + memcpy(&new->lru, &old->lru, flex_array_size(new, lru, old_size)); /* * The locking below allows readers that hold nlru->lock avoid taking |