Commit c1755c25 authored by Breno Leitao's avatar Breno Leitao Committed by Jens Axboe
Browse files

io_uring: Enable KASAN for request cache 



Every io_uring request is represented by struct io_kiocb, which is
cached locally by io_uring (not SLAB/SLUB) in the list called
submit_state.freelist. This patch simply enabled KASAN for this free
list.

This list is initially created by KMEM_CACHE, but later, managed by
io_uring. This patch basically poisons the objects that are not used
(i.e., they are the free list), and unpoisons it when the object is
allocated/removed from the list.

Touching these poisoned objects while in the freelist will cause a KASAN
warning.

Suggested-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Reviewed-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent b5d3ae20

io_uring/io_uring.c

+2 −1
Original line number Diff line number Diff line
@@ -151,7 +151,7 @@ static void io_move_task_work_from_local(struct io_ring_ctx *ctx); 
static void __io_submit_flush_completions(struct io_ring_ctx *ctx);

static __cold void io_fallback_tw(struct io_uring_task *tctx);



static struct kmem_cache *req_cachep;

struct kmem_cache *req_cachep;



struct sock *io_uring_get_socket(struct file *file)

{
@@ -230,6 +230,7 @@ static inline void req_fail_link_node(struct io_kiocb *req, int res) 
static inline void io_req_add_to_cache(struct io_kiocb *req, struct io_ring_ctx *ctx)

{

	wq_stack_add_head(&req->comp_list, &ctx->submit_state.free_list);

	kasan_poison_object_data(req_cachep, req);

}



static __cold void io_ring_ctx_ref_free(struct percpu_ref *ref)

io_uring/io_uring.h

+8 −3
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <linux/errno.h>

#include <linux/lockdep.h>

#include <linux/resume_user_mode.h>

#include <linux/kasan.h>

#include <linux/io_uring_types.h>

#include <uapi/linux/eventpoll.h>

#include "io-wq.h"
@@ -347,12 +348,16 @@ static inline bool io_alloc_req_refill(struct io_ring_ctx *ctx) 
	return true;

}



extern struct kmem_cache *req_cachep;



static inline struct io_kiocb *io_alloc_req(struct io_ring_ctx *ctx)

{

	struct io_wq_work_node *node;

	struct io_kiocb *req;



	node = wq_stack_extract(&ctx->submit_state.free_list);

	return container_of(node, struct io_kiocb, comp_list);

	req = container_of(ctx->submit_state.free_list.next, struct io_kiocb, comp_list);

	kasan_unpoison_object_data(req_cachep, req);

	wq_stack_extract(&ctx->submit_state.free_list);

	return req;

}



static inline bool io_allowed_defer_tw_run(struct io_ring_ctx *ctx)