[PATCH 3/5] bpf: Improve exception handling in bpf_core_apply()

[Markus Elfring]

From: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
Date: Sat, 30 Dec 2023 19:28:25 +0100

The kfree() function was called in two cases by
the bpf_core_apply() function during error handling
even if the passed data structure member contained a null pointer.
This issue was detected by using the Coccinelle software.

* Thus use another label.

* Reorder function calls at the end.

Signed-off-by: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
---
 kernel/bpf/btf.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 51e8b4bee0c8..e8391025d408 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -8322,13 +8322,13 @@ int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo,
 			bpf_log(ctx->log, "target candidate search failed for %d\n",
 				relo->type_id);
 			err = PTR_ERR(cc);
-			goto out;
+			goto unlock_mutex;
 		}
 		if (cc->cnt) {
 			cands.cands = kcalloc(cc->cnt, sizeof(*cands.cands), GFP_KERNEL);
 			if (!cands.cands) {
 				err = -ENOMEM;
-				goto out;
+				goto unlock_mutex;
 			}
 		}
 		for (i = 0; i < cc->cnt; i++) {
@@ -8355,13 +8355,15 @@ int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo,
 				  &targ_res);

 out:
-	kfree(specs);
 	if (need_cands) {
 		kfree(cands.cands);
+unlock_mutex:
 		mutex_unlock(&cand_cache_mutex);
 		if (ctx->log->level & BPF_LOG_LEVEL2)
 			print_cand_cache(ctx->log);
 	}
+
+	kfree(specs);
 	return err;
 }

--
2.43.0