linux-kernel - [PATCH 5.4 147/309] libbpf: Fix realloc usage in bpf_core_find

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Message-Id: <20200210122420.451093285@linuxfoundation.org>
Date:   Mon, 10 Feb 2020 04:31:43 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, William Smith <williampsmith@...com>,
        Andrii Nakryiko <andriin@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Yonghong Song <yhs@...com>
Subject: [PATCH 5.4 147/309] libbpf: Fix realloc usage in bpf_core_find_cands

From: Andrii Nakryiko <andriin@...com>

commit 35b9211c0a2427e8f39e534f442f43804fc8d5ca upstream.

Fix bug requesting invalid size of reallocated array when constructing CO-RE
relocation candidate list. This can cause problems if there are many potential
candidates and a very fine-grained memory allocator bucket sizes are used.

Fixes: ddc7c3042614 ("libbpf: implement BPF CO-RE offset relocation algorithm")
Reported-by: William Smith <williampsmith@...com>
Signed-off-by: Andrii Nakryiko <andriin@...com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: Yonghong Song <yhs@...com>
Link: https://lore.kernel.org/bpf/20200124201847.212528-1-andriin@fb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 tools/lib/bpf/libbpf.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2541,7 +2541,9 @@ static struct ids_vec *bpf_core_find_can
 		if (strncmp(local_name, targ_name, local_essent_len) == 0) {
 			pr_debug("[%d] %s: found candidate [%d] %s\n",
 				 local_type_id, local_name, i, targ_name);
-			new_ids = realloc(cand_ids->data, cand_ids->len + 1);
+			new_ids = reallocarray(cand_ids->data,
+					       cand_ids->len + 1,
+					       sizeof(*cand_ids->data));
 			if (!new_ids) {
 				err = -ENOMEM;
 				goto err_out;