linux-kernel - [PATCH v3] selftests/capabilities: Fix possible file leak in copy_fromat

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Date: Sun, 30 Jun 2024 21:00:38 +0800
From: Ma Ke <make24@...as.ac.cn>
To: shuah@...nel.org,
	usama.anjum@...labora.com,
	swarupkotikalapudi@...il.com,
	make24@...as.ac.cn,
	amer.shanawany@...il.com,
	kees@...nel.org,
	akpm@...ux-foundation.org,
	luto@...nel.org
Cc: linux-kselftest@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v3] selftests/capabilities: Fix possible file leak in copy_fromat_to

The open() function returns -1 on error. openat() and open() initialize
'from' and 'to', and only 'from' validated with 'if' statement. If the
initialization of variable 'to' fails, we should better check the value
of 'to' and close 'from' to avoid possible file leak. Improve the checking
of 'from' additionally.

Fixes: 32ae976ed3b5 ("selftests/capabilities: Add tests for capability evolution")
Signed-off-by: Ma Ke <make24@...as.ac.cn>
---
Changes in v3:
- Thank you for your interest in our vulnerability detection method. We 
extract vulnerability characteristics from a known vulnerability and match 
the same characteristics in the project code. As our work is still in 
progress, we are not able to disclose it at this time. Appreciate your 
understanding, we could better focus on the potential vulnerability itself.
Reference link: https://lore.kernel.org/all/20240510003424.2016914-1-samasth.norway.ananda@oracle.com/
Changes in v2:
- modified the patch according to suggestions;
- found by customized static analysis tool.
---
 tools/testing/selftests/capabilities/test_execve.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/capabilities/test_execve.c b/tools/testing/selftests/capabilities/test_execve.c
index 47bad7ddc5bc..6406ab6aa1f5 100644
--- a/tools/testing/selftests/capabilities/test_execve.c
+++ b/tools/testing/selftests/capabilities/test_execve.c
@@ -145,10 +145,14 @@ static void chdir_to_tmpfs(void)
 static void copy_fromat_to(int fromfd, const char *fromname, const char *toname)
 {
 	int from = openat(fromfd, fromname, O_RDONLY);
-	if (from == -1)
+	if (from < 0)
 		ksft_exit_fail_msg("open copy source - %s\n", strerror(errno));
 
 	int to = open(toname, O_CREAT | O_WRONLY | O_EXCL, 0700);
+	if (to < 0) {
+		close(from);
+		ksft_exit_fail_msg("open copy destination - %s\n", strerror(errno));
+	}
 
 	while (true) {
 		char buf[4096];
-- 
2.25.1