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authorMatthew Wilcox (Oracle) <willy@infradead.org>2020-10-09 13:49:52 +0100
committerJens Axboe <axboe@kernel.dk>2020-10-12 14:59:33 -0600
commit057576b74842364ee5ab87d361f7dc42f96653b3 (patch)
tree6f1e2c3884855d48fa54010d71b4c4c368b91314
parent282757c38c41e30a8dc0098eb8f6d879acf0553b (diff)
io_uring: Fix XArray usage in io_uring_add_task_file
commit 236434c3438c4da3dfbd6aeeab807577b85e951a upstream. The xas_store() wasn't paired with an xas_nomem() loop, so if it couldn't allocate memory using GFP_NOWAIT, it would leak the reference to the file descriptor. Also the node pointed to by the xas could be freed between the call to xas_load() under the rcu_read_lock() and the acquisition of the xa_lock. It's easier to just use the normal xa_load/xa_store interface here. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> [axboe: fix missing assign after alloc, cur_uring -> tctx rename] Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/io_uring.c21
1 files changed, 9 insertions, 12 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 2bd6f0a48fd3..98f4c2789391 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7929,27 +7929,24 @@ static void io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
*/
static int io_uring_add_task_file(struct file *file)
{
- if (unlikely(!current->io_uring)) {
+ struct io_uring_task *tctx = current->io_uring;
+
+ if (unlikely(!tctx)) {
int ret;
ret = io_uring_alloc_task_context(current);
if (unlikely(ret))
return ret;
+ tctx = current->io_uring;
}
- if (current->io_uring->last != file) {
- XA_STATE(xas, &current->io_uring->xa, (unsigned long) file);
- void *old;
+ if (tctx->last != file) {
+ void *old = xa_load(&tctx->xa, (unsigned long)file);
- rcu_read_lock();
- old = xas_load(&xas);
- if (old != file) {
+ if (!old) {
get_file(file);
- xas_lock(&xas);
- xas_store(&xas, file);
- xas_unlock(&xas);
+ xa_store(&tctx->xa, (unsigned long)file, file, GFP_KERNEL);
}
- rcu_read_unlock();
- current->io_uring->last = file;
+ tctx->last = file;
}
return 0;