libbpf: Fix memory leak in btf__dedup()

mainline inclusion
from mainline-5.16-rc1
commit 1000298c
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1000298c76830bc291358e98e8fa5baa3baa9b3a

-------------------------------------------------

Free btf_dedup if btf_ensure_modifiable() returns error.

Fixes: 919d2b1d ("libbpf: Allow modification of BTF and add btf__add_str API")
Signed-off-by: NMauricio Vásquez <mauricio@kinvolk.io>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211022202035.48868-1-mauricio@kinvolk.io
(cherry picked from commit 1000298c)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

tools/lib/bpf/btf.c

@@ -2997,8 +2997,10 @@ int btf__dedup(struct btf *btf, struct btf_ext *btf_ext,
 		return libbpf_err(-EINVAL);
 	}
 
-	if (btf_ensure_modifiable(btf))
-		return libbpf_err(-ENOMEM);
+	if (btf_ensure_modifiable(btf)) {
+		err = -ENOMEM;
+		goto done;
+	}
 
 	err = btf_dedup_prep(d);
 	if (err) {