From: Justin Stitt <justinstitt@google.com>
To: reiserfs-devel@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: linux-hardening@vger.kernel.org, Justin Stitt <justinstitt@google.com>
Subject: [PATCH] reiserfs: replace deprecated strncpy with scnprintf
Date: Thu, 28 Mar 2024 21:16:52 +0000 [thread overview]
Message-ID: <20240328-strncpy-fs-reiserfs-item_ops-c-v1-1-2dab6d22a996@google.com> (raw)
strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
Our goal here is to get @namebuf populated with @name's contents but
surrounded with quotes. There is some careful handling done to ensure we
properly truncate @name so that we have room for a literal quote as well
as a NUL-term. All this careful handling can be done with scnprintf
using the dynamic string width specifier %.*s which allows us to pass in
the max size for a source string. Doing this, we can put literal quotes
in our format specifier and ensure @name is truncated to fit inbetween
these quotes (-3 is from 2 quotes + 1 NUL-byte).
All in all, we get to remove a deprecated use of strncpy and clean up
this code nicely!
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
I realize this file has been marked as "obsolete" as told by checkpatch:
| WARNING: fs/reiserfs/item_ops.c is marked as 'obsolete' in the MAINTAINERS hierarchy. No unnecessary modifications please.
... but I really want to remove ALL instances of strncpy so we can rip
it out of the kernel as per: https://github.com/KSPP/linux/issues/90.
---
fs/reiserfs/item_ops.c | 13 +++----------
1 file changed, 3 insertions(+), 10 deletions(-)
diff --git a/fs/reiserfs/item_ops.c b/fs/reiserfs/item_ops.c
index 3a5a752d96c7..5011c10287c6 100644
--- a/fs/reiserfs/item_ops.c
+++ b/fs/reiserfs/item_ops.c
@@ -389,16 +389,9 @@ static void direntry_print_item(struct item_head *ih, char *item)
name = item + deh_location(deh);
if (name[namelen - 1] == 0)
namelen = strlen(name);
- namebuf[0] = '"';
- if (namelen > sizeof(namebuf) - 3) {
- strncpy(namebuf + 1, name, sizeof(namebuf) - 3);
- namebuf[sizeof(namebuf) - 2] = '"';
- namebuf[sizeof(namebuf) - 1] = 0;
- } else {
- memcpy(namebuf + 1, name, namelen);
- namebuf[namelen + 1] = '"';
- namebuf[namelen + 2] = 0;
- }
+
+ scnprintf(namebuf, sizeof(namebuf), "\"%.*s\"",
+ (int)sizeof(namebuf)-3, name);
printk("%d: %-15s%-15d%-15d%-15lld%-15lld(%s)\n",
i, namebuf,
---
base-commit: 928a87efa42302a23bb9554be081a28058495f22
change-id: 20240328-strncpy-fs-reiserfs-item_ops-c-c2f9b8a6c1f3
Best regards,
--
Justin Stitt <justinstitt@google.com>
next reply other threads:[~2024-03-28 21:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-28 21:16 Justin Stitt [this message]
2024-03-28 22:06 ` [PATCH] reiserfs: replace deprecated strncpy with scnprintf Kees Cook
2024-04-24 23:54 ` Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240328-strncpy-fs-reiserfs-item_ops-c-v1-1-2dab6d22a996@google.com \
--to=justinstitt@google.com \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=reiserfs-devel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).