linux-kernel - [PATCH v2] of: overlay: fix null pointer dereferencing in find_dup_cset_node_entry() and find_dup_cset

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Message-ID: <20221211023337.592266-1-ruanjinjie@huawei.com>
Date:   Sun, 11 Dec 2022 10:33:37 +0800
From:   ruanjinjie <ruanjinjie@...wei.com>
To:     <robh+dt@...nel.org>, <frowand.list@...il.com>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <ruanjinjie@...wei.com>
Subject: [PATCH v2] of: overlay: fix null pointer dereferencing in find_dup_cset_node_entry() and find_dup_cset_prop()

when kmalloc() fail to allocate memory in kasprintf(), fn_1 or fn_2 will
be NULL, strcmp() will cause null pointer dereference.

Fixes: 2fe0e8769df9 ("of: overlay: check prevents multiple fragments touching same property")
Signed-off-by: ruanjinjie <ruanjinjie@...wei.com>
---
v2:
- not care return code, so check whether fn_1 or fn_2 is NULL in assigning node_path_match
---
 drivers/of/overlay.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index bd8ff4df723d..ed4e6c144a68 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -545,7 +545,7 @@ static int find_dup_cset_node_entry(struct overlay_changeset *ovcs,
 
 		fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
 		fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
-		node_path_match = !strcmp(fn_1, fn_2);
+		node_path_match = !fn_1 || !fn_2 || !strcmp(fn_1, fn_2);
 		kfree(fn_1);
 		kfree(fn_2);
 		if (node_path_match) {
@@ -580,7 +580,7 @@ static int find_dup_cset_prop(struct overlay_changeset *ovcs,
 
 		fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
 		fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
-		node_path_match = !strcmp(fn_1, fn_2);
+		node_path_match = !fn_1 || !fn_2 || !strcmp(fn_1, fn_2);
 		kfree(fn_1);
 		kfree(fn_2);
 		if (node_path_match &&
-- 
2.25.1