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@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 9e15c3a0ced5a61f320b989072c24983cb1620c1 Mon Sep 17 00:00:00 2001
From: Jens Axboe axboe@kernel.dk 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@vger.kernel.org Cc: Matthew Wilcox willy@infradead.org Cc: yangerkun yangerkun@huawei.com Reported-by: Hulk Robot hulkci@huawei.com Signed-off-by: Jens Axboe axboe@kernel.dk
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)