linux-kernel - [PATCH 01/27] modpost: use snprintf() instead of sprintf() for safety

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Date:   Mon, 25 Apr 2022 04:07:45 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     linux-kbuild@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: [PATCH 01/27] modpost: use snprintf() instead of sprintf() for safety

Use snprintf() to avoid the potential buffer overflow, and also
check the return value to detect the too long path.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

 scripts/mod/modpost.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 522d5249d196..141370ebbfd3 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2560,6 +2560,7 @@ int main(int argc, char **argv)
 
 	for (mod = modules; mod; mod = mod->next) {
 		char fname[PATH_MAX];
+		int ret;
 
 		if (mod->is_vmlinux || mod->from_dump)
 			continue;
@@ -2578,7 +2579,12 @@ int main(int argc, char **argv)
 		add_moddevtable(&buf, mod);
 		add_srcversion(&buf, mod);
 
-		sprintf(fname, "%s.mod.c", mod->name);
+		ret = snprintf(fname, sizeof(fname), "%s.mod.c", mod->name);
+		if (ret >= sizeof(fname)) {
+			error("%s: too long path was truncated\n", fname);
+			continue;
+		}
+
 		write_if_changed(&buf, fname);
 	}
 
-- 
2.32.0