[PATCH 1/1] io_uring/rsrc: fix rogue rsrc node grabbing

[Pavel Begunkov <asml.silence@gmail.com>]

We should not be looking at ctx->rsrc_node and anyhow modifying the node
without holding uring_lock, grabbing references in such a way is not
safe either.

Cc: stable@vger.kernel.org
Fixes: 5106dd6e74ab6 ("io_uring: propagate issue_flags state down to file assignment")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/rsrc.h | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 2b8743645efc..f27f4975217d 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -144,15 +144,13 @@ static inline void io_req_set_rsrc_node(struct io_kiocb *req,
 					unsigned int issue_flags)
 {
 	if (!req->rsrc_node) {
-		req->rsrc_node = ctx->rsrc_node;
+		io_ring_submit_lock(ctx, issue_flags);
 
-		if (!(issue_flags & IO_URING_F_UNLOCKED)) {
-			lockdep_assert_held(&ctx->uring_lock);
+		lockdep_assert_held(&ctx->uring_lock);
 
-			io_charge_rsrc_node(ctx);
-		} else {
-			percpu_ref_get(&req->rsrc_node->refs);
-		}
+		req->rsrc_node = ctx->rsrc_node;
+		io_charge_rsrc_node(ctx);
+		io_ring_submit_unlock(ctx, issue_flags);
 	}
 }
 
-- 
2.39.1