linux-ext4 - [PATCH 30/38] misc/fuse2fs: avoid error-prone strncpy() pattern

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sat, 21 Jan 2023 12:32:22 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     linux-ext4@...r.kernel.org
Subject: [PATCH 30/38] misc/fuse2fs: avoid error-prone strncpy() pattern

From: Eric Biggers <ebiggers@...gle.com>

'strncpy(dst, src, strlen(src))' is usually wrong, as it doesn't copy
the null terminator.  For this reason, it causes a -Wstringop-truncation
warning with gcc 8 and later.

The code happens to be correct anyway, since the destination buffer is
zero-initialized.  But to avoid relying on this, let's just copy the
terminating null.

Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
 misc/fuse2fs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index c59572129..6d4bcf4fd 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -2508,9 +2508,10 @@ static int copy_names(char *name, char *value EXT2FS_ATTR((unused)),
 		      size_t value_len EXT2FS_ATTR((unused)), void *data)
 {
 	char **b = data;
+	size_t name_len = strlen(name);
 
-	strncpy(*b, name, strlen(name));
-	*b = *b + strlen(name) + 1;
+	memcpy(*b, name, name_len + 1);
+	*b = *b + name_len + 1;
 
 	return 0;
 }
-- 
2.39.0