Breno Leitao <leitao@xxxxxxxxxx> writes:
> Add support for KASAN in the alloc_caches (apoll and netmsg_cache).
> Thus, if something touches the unused caches, it will raise a KASAN
> warning/exception.
>
> It poisons the object when the object is put to the cache, and unpoisons
> it when the object is gotten or freed.
>
> Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
> ---
> include/linux/io_uring_types.h | 1 +
> io_uring/alloc_cache.h | 6 +++++-
> io_uring/io_uring.c | 4 ++--
> io_uring/net.h | 5 ++++-
> 4 files changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
> index efa66b6c32c9..35ebcfb46047 100644
> --- a/include/linux/io_uring_types.h
> +++ b/include/linux/io_uring_types.h
> @@ -190,6 +190,7 @@ struct io_ev_fd {
> struct io_alloc_cache {
> struct io_wq_work_node list;
> unsigned int nr_cached;
> + size_t elem_size;
> };
>
> struct io_ring_ctx {
> diff --git a/io_uring/alloc_cache.h b/io_uring/alloc_cache.h
> index 301855e94309..3aba7b356320 100644
> --- a/io_uring/alloc_cache.h
> +++ b/io_uring/alloc_cache.h
> @@ -16,6 +16,8 @@ static inline bool io_alloc_cache_put(struct io_alloc_cache *cache,
> if (cache->nr_cached < IO_ALLOC_CACHE_MAX) {
> cache->nr_cached++;
> wq_stack_add_head(&entry->node, &cache->list);
> + /* KASAN poisons object */
> + kasan_slab_free_mempool(entry);
> return true;
> }
> return false;
> @@ -27,6 +29,7 @@ static inline struct io_cache_entry *io_alloc_cache_get(struct io_alloc_cache *c
> struct io_cache_entry *entry;
>
> entry = container_of(cache->list.next, struct io_cache_entry, node);
> + kasan_unpoison_range(entry, cache->elem_size);
I kind of worry there is no type checking at the same time we are
unpoisoning a constant-size range. Seems easy to misuse the API. But it
does look much better now with elem_size cached inside io_alloc_cache.
>
> -#if defined(CONFIG_NET)
> struct io_async_msghdr {
> +#if defined(CONFIG_NET)
> union {
> struct iovec fast_iov[UIO_FASTIOV];
> struct {
> @@ -22,8 +22,11 @@ struct io_async_msghdr {
> struct sockaddr __user *uaddr;
> struct msghdr msg;
> struct sockaddr_storage addr;
> +#endif
> };
>
> +#if defined(CONFIG_NET)
> +
Nit, but you could have added an empty definition in the #else section
that already exists in the file, or just guarded the caching code
entirely when CONFIG_NET=n.
Just nits, and overall it is good to have this KASAN support!
Reviewed-by: Gabriel Krisman Bertazi <krisman@xxxxxxx>
--
Gabriel Krisman Bertazi
