[PATCH v1] tracing/remotes: Fix leak in trace_remote_alloc_buffer() error path

[Vincent Donnefort <vdonnefort@google.com>]

If page allocation fails in trace_remote_alloc_buffer(), desc->nr_cpus
is not yet incremented for the current CPU. As a consequence, on error,
half-allocated rb_desc will not be freed in trace_remote_free_buffer().

Include the failing CPU in desc->nr_cpus before going to the error path.

Fixes: 96e43537af54 ("tracing: Introduce trace remotes")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c
index 2a6cc000ec98..62d3d431c309 100644
--- a/kernel/trace/trace_remote.c
+++ b/kernel/trace/trace_remote.c
@@ -1008,8 +1008,10 @@ int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_size,
 
 		for (id = 0; id < nr_pages; id++) {
 			rb_desc->page_va[id] = (unsigned long)__get_free_page(GFP_KERNEL);
-			if (!rb_desc->page_va[id])
+			if (!rb_desc->page_va[id]) {
+				desc->nr_cpus++; /* Free this partially-allocated rb_desc */
 				goto err;
+			}
 
 			rb_desc->nr_page_va++;
 		}

base-commit: 8cdeaa50eae8dad34885515f62559ee83e7e8dda
-- 
2.55.0.795.g602f6c329a-goog