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Message-ID: <20240328-strncpy-fs-squashfs-namei-c-v1-1-5c7bcbbeb675@google.com>
Date: Thu, 28 Mar 2024 21:52:59 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Phillip Lougher <phillip@...ashfs.org.uk>
Cc: linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] Squashfs: replace deprecated strncpy with strscpy
strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
The previous code took special care of NUL-terminating the destination
buffer via a manual assignment. As such, there is no bug in the current
implementation. However, in an effort to rid the kernel of strscpy()
[2], Let's instead use strscpy() which guarantees this behavior [3]. To
ensure we can copy the same number of bytes as before, add 1 to the
length argument provided to strscpy().
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90 [2]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [3]
Cc: linux-hardening@...r.kernel.org
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Note: build-tested only.
Found with: $ rg "strncpy\("
---
fs/squashfs/namei.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/squashfs/namei.c b/fs/squashfs/namei.c
index 11e4539b9eae..6c4704ba8f42 100644
--- a/fs/squashfs/namei.c
+++ b/fs/squashfs/namei.c
@@ -80,8 +80,7 @@ static int get_dir_index_using_name(struct super_block *sb,
}
str = &index->name[SQUASHFS_NAME_LEN + 1];
- strncpy(str, name, len);
- str[len] = '\0';
+ strscpy(str, name, len + 1);
for (i = 0; i < i_count; i++) {
err = squashfs_read_metadata(sb, index, &index_start,
---
base-commit: 928a87efa42302a23bb9554be081a28058495f22
change-id: 20240328-strncpy-fs-squashfs-namei-c-9d01b8975e53
Best regards,
--
Justin Stitt <justinstitt@...gle.com>
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