From: Martin Wilck <martin_wilck@gmx.de>
Date: Fri, 15 Nov 2024 22:26:26 +0000 (+0100)
Subject: libkmod: strbuf_pushchars: handle pushing empty string gracefully
X-Git-Tag: v34~43
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5f154ec21e0081daf8a02e3b6b1bf3836bb05801;p=thirdparty%2Fkmod.git

libkmod: strbuf_pushchars: handle pushing empty string gracefully

If buf->bytes, buf->used, and len are all 0, buf_grow() will do nothing,
and memcpy() willbe called with a NULL first argument. This will cause
an error because the function is annotated with __nonnull(1, 2).

Fixes: e62d8c7 ("strbuf: make strbuf_pushchars() a little less dumb")
Signed-off-by: Martin Wilck <martin_wilck@gmx.de>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/257
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
---

diff --git a/shared/strbuf.c b/shared/strbuf.c
index dad5da52..0dd7a5b0 100644
--- a/shared/strbuf.c
+++ b/shared/strbuf.c
@@ -100,6 +100,9 @@ size_t strbuf_pushmem(struct strbuf *buf, const char *src, size_t sz)
 	assert(src != NULL);
 	assert(buf != NULL);
 
+	if (sz == 0)
+		return 0;
+
 	if (!strbuf_reserve_extra(buf, sz))
 		return 0;
 
diff --git a/testsuite/test-strbuf.c b/testsuite/test-strbuf.c
index 9f2dcf8f..50c75d92 100644
--- a/testsuite/test-strbuf.c
+++ b/testsuite/test-strbuf.c
@@ -202,8 +202,7 @@ static int test_strbuf_pushmem(const struct test *t)
 
 	return 0;
 }
-DEFINE_TEST(test_strbuf_pushmem, .description = "test strbuf_reserve",
-	    .expected_fail = true);
+DEFINE_TEST(test_strbuf_pushmem, .description = "test strbuf_reserve");
 
 static int test_strbuf_used(const struct test *t)
 {