The patch below does not apply to the 5.11-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 9e15c3a0ced5a61f320b989072c24983cb1620c1 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Sat, 13 Mar 2021 12:29:43 -0700
Subject: [PATCH] io_uring: convert io_buffer_idr to XArray
Like we did for the personality idr, convert the IO buffer idr to use
XArray. This avoids a use-after-free on removal of entries, since idr
doesn't like doing so from inside an iterator, and it nicely reduces
the amount of code we need to support this feature.
Fixes: 5a2e745d4d43 ("io_uring: buffer registration infrastructure")
Cc: stable@xxxxxxxxxxxxxxx
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: yangerkun <yangerkun@xxxxxxxxxx>
Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 05adc4887ef3..58d62dd9f8e4 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -402,7 +402,7 @@ struct io_ring_ctx {
struct socket *ring_sock;
#endif
- struct idr io_buffer_idr;
+ struct xarray io_buffers;
struct xarray personalities;
u32 pers_next;
@@ -1135,7 +1135,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
init_waitqueue_head(&ctx->cq_wait);
INIT_LIST_HEAD(&ctx->cq_overflow_list);
init_completion(&ctx->ref_comp);
- idr_init(&ctx->io_buffer_idr);
+ xa_init_flags(&ctx->io_buffers, XA_FLAGS_ALLOC1);
xa_init_flags(&ctx->personalities, XA_FLAGS_ALLOC1);
mutex_init(&ctx->uring_lock);
init_waitqueue_head(&ctx->wait);
@@ -2843,7 +2843,7 @@ static struct io_buffer *io_buffer_select(struct io_kiocb *req, size_t *len,
lockdep_assert_held(&req->ctx->uring_lock);
- head = idr_find(&req->ctx->io_buffer_idr, bgid);
+ head = xa_load(&req->ctx->io_buffers, bgid);
if (head) {
if (!list_empty(&head->list)) {
kbuf = list_last_entry(&head->list, struct io_buffer,
@@ -2851,7 +2851,7 @@ static struct io_buffer *io_buffer_select(struct io_kiocb *req, size_t *len,
list_del(&kbuf->list);
} else {
kbuf = head;
- idr_remove(&req->ctx->io_buffer_idr, bgid);
+ xa_erase(&req->ctx->io_buffers, bgid);
}
if (*len > kbuf->len)
*len = kbuf->len;
@@ -3892,7 +3892,7 @@ static int __io_remove_buffers(struct io_ring_ctx *ctx, struct io_buffer *buf,
}
i++;
kfree(buf);
- idr_remove(&ctx->io_buffer_idr, bgid);
+ xa_erase(&ctx->io_buffers, bgid);
return i;
}
@@ -3910,7 +3910,7 @@ static int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags)
lockdep_assert_held(&ctx->uring_lock);
ret = -ENOENT;
- head = idr_find(&ctx->io_buffer_idr, p->bgid);
+ head = xa_load(&ctx->io_buffers, p->bgid);
if (head)
ret = __io_remove_buffers(ctx, head, p->bgid, p->nbufs);
if (ret < 0)
@@ -3993,21 +3993,14 @@ static int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags)
lockdep_assert_held(&ctx->uring_lock);
- list = head = idr_find(&ctx->io_buffer_idr, p->bgid);
+ list = head = xa_load(&ctx->io_buffers, p->bgid);
ret = io_add_buffers(p, &head);
- if (ret < 0)
- goto out;
-
- if (!list) {
- ret = idr_alloc(&ctx->io_buffer_idr, head, p->bgid, p->bgid + 1,
- GFP_KERNEL);
- if (ret < 0) {
+ if (ret >= 0 && !list) {
+ ret = xa_insert(&ctx->io_buffers, p->bgid, head, GFP_KERNEL);
+ if (ret < 0)
__io_remove_buffers(ctx, head, p->bgid, -1U);
- goto out;
- }
}
-out:
if (ret < 0)
req_set_fail_links(req);
@@ -8333,19 +8326,13 @@ static int io_eventfd_unregister(struct io_ring_ctx *ctx)
return -ENXIO;
}
-static int __io_destroy_buffers(int id, void *p, void *data)
-{
- struct io_ring_ctx *ctx = data;
- struct io_buffer *buf = p;
-
- __io_remove_buffers(ctx, buf, id, -1U);
- return 0;
-}
-
static void io_destroy_buffers(struct io_ring_ctx *ctx)
{
- idr_for_each(&ctx->io_buffer_idr, __io_destroy_buffers, ctx);
- idr_destroy(&ctx->io_buffer_idr);
+ struct io_buffer *buf;
+ unsigned long index;
+
+ xa_for_each(&ctx->io_buffers, index, buf)
+ __io_remove_buffers(ctx, buf, index, -1U);
}
static void io_req_cache_free(struct list_head *list, struct task_struct *tsk)
