[PATCH] KVM: arm64: Fix potential leak in hyp_trace_buffer_alloc_bpages_backing

[Vincent Donnefort <vdonnefort@google.com>]

In the very unlikely event of a failure in __map_hyp, the allocated
backing pages are leaked in hyp_trace_buffer_alloc_bpages_backing(). Fix
this by freeing the pages on error.

Fixes: 3aed038aac8d ("KVM: arm64: Add trace remote for the nVHE/pKVM hyp")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

diff --git a/arch/arm64/kvm/hyp_trace.c b/arch/arm64/kvm/hyp_trace.c
index 2411b4c32932..5fbbfd40376f 100644
--- a/arch/arm64/kvm/hyp_trace.c
+++ b/arch/arm64/kvm/hyp_trace.c
@@ -160,6 +160,7 @@ static int hyp_trace_buffer_alloc_bpages_backing(struct hyp_trace_buffer *trace_
 	int nr_bpages = (PAGE_ALIGN(size) / PAGE_SIZE) + 1;
 	size_t backing_size;
 	void *start;
+	int ret;
 
 	backing_size = PAGE_ALIGN(sizeof(struct simple_buffer_page) * nr_bpages *
 				  num_possible_cpus());
@@ -171,7 +172,11 @@ static int hyp_trace_buffer_alloc_bpages_backing(struct hyp_trace_buffer *trace_
 	trace_buffer->desc->bpages_backing_start = (unsigned long)start;
 	trace_buffer->desc->bpages_backing_size = backing_size;
 
-	return __map_hyp(start, backing_size);
+	ret = __map_hyp(start, backing_size);
+	if (ret)
+		free_pages_exact(start, backing_size);
+
+	return ret;
 }
 
 static void hyp_trace_buffer_free_bpages_backing(struct hyp_trace_buffer *trace_buffer)

base-commit: 8cdeaa50eae8dad34885515f62559ee83e7e8dda
-- 
2.55.0.rc2.803.g1fd1e6609c-goog