From c1755c25a7190494b45861284b4a30bd9cd813ff Mon Sep 17 00:00:00 2001
From: Breno Leitao <leitao@debian.org>
Date: Wed, 18 Jan 2023 07:56:30 -0800
Subject: [PATCH] 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: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
io_uring/io_uring.c | 3 ++-
io_uring/io_uring.h | 11 ++++++++---
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index c84dce6944db9..407834255a592 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -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)
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index d58cfe062da90..9270156288aad 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -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)
--
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