Message ID | 20231130201222.3613535-2-keescook@chromium.org |
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State | New |
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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id w20-20020a170902a71400b001d0242c0471sm1794719plq.224.2023.11.30.12.12.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Nov 2023 12:12:23 -0800 (PST) From: Kees Cook <keescook@chromium.org> To: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Kees Cook <keescook@chromium.org>, Tejun Heo <tj@kernel.org>, Azeem Shaikh <azeemshaikh38@gmail.com>, Zefan Li <lizefan.x@bytedance.com>, Johannes Weiner <hannes@cmpxchg.org>, Waiman Long <longman@redhat.com>, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, bpf@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2 2/3] kernfs: Convert kernfs_name_locked() from strlcpy() to strscpy() Date: Thu, 30 Nov 2023 12:12:18 -0800 Message-Id: <20231130201222.3613535-2-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231130200937.it.424-kees@kernel.org> References: <20231130200937.it.424-kees@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2637; i=keescook@chromium.org; h=from:subject; bh=JAJdaxInWUYVNuwIwA8b/GPyHonLetqQSJoS2H+M0wM=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlaOyjBNLwq83oMtldatGW+UhXwbgyaP8FTFySX SrtWyh/9ueJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZWjsowAKCRCJcvTf3G3A Jm5zEAClKw3heuKsLAxhXMgbSIvAPXK7qmEyDktGCUWVn1nRNWVFKPNbaM01zKM6050NbOlC/Dn uHrkNUwjUwO7nl6cOoI/ErwkWj2InKd2UEFHBUT6pyggumpGWZNGf2epzUNP3DCJzOeqisxmzmD uPN3+cV/yRUGoq6iq8EbLsxDUJSHugfyoLTcOWPwP8hKqBj4GPSNCFhpH5ZPEQCMqACjPOu75j+ 3+KwBNLt7nLsTn7ilAVoU6TeRmlmnv4tAcwJvyCnxMmAuDcDgUsqOwhYcgC8oaLVtrLq0iwDbvQ d2mJGliCeakISYslS0pxjlvSWeDJOByZqMADBLBuGZNR/s3UhTqI8drb12NldkzMm8D9JovJmMk pRdfjGXUFNyfN5DemTVLaAPtyVj+gTVMJADvEVjgsrq0VYa1aLze+oSJrdDC+zYUQwCdF45ov/w /tF0FwTz0byrsC+ytvYt0nw1i7ZdFuMoqoouLFMnPt5o3gpVcwcDFeT9y39usX08lUVfbsCKskj NbbDSDRzieaHqFBWAs+hFF8O3E02Kk+Y9moy6eang5KQgS3ahdWwW3WDKuygWRZ/ZT4kTh4ECN6 AF8ycj65cPRGIh1uBMGlaLk5MNeGMk07XH5aiPhWTCHOuGSqnzeFqy6MCC8VAisSJ2ZCeEBWPVt 71IQ/lmUUzgov6Q== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: <linux-kernel.vger.kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Thu, 30 Nov 2023 12:12:32 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1784021152754485051 X-GMAIL-MSGID: 1784021152754485051 |
Series |
kernfs: Convert from strlcpy() to strscpy()
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Commit Message
Kees Cook
Nov. 30, 2023, 8:12 p.m. UTC
strlcpy() reads the entire source buffer first. This read may exceed
the destination size limit. This is both inefficient and can lead
to linear read overflows if a source string is not NUL-terminated[1].
Additionally, it returns the size of the source string, not the
resulting size of the destination string. In an effort to remove strlcpy()
completely[2], replace strlcpy() here with strscpy().
Nothing actually checks the return value coming from kernfs_name_locked(),
so this has no impact on error paths. The caller hierarchy is:
kernfs_name_locked()
kernfs_name()
pr_cont_kernfs_name()
return value ignored
cgroup_name()
current_css_set_cg_links_read()
return value ignored
print_page_owner_memcg()
return value ignored
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1]
Link: https://github.com/KSPP/linux/issues/89 [2]
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Azeem Shaikh <azeemshaikh38@gmail.com>
Link: https://lore.kernel.org/r/20231116192127.1558276-2-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
fs/kernfs/dir.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 37353901ede1..8c0e5442597e 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -54,9 +54,9 @@ static bool kernfs_lockdep(struct kernfs_node *kn) static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen) { if (!kn) - return strlcpy(buf, "(null)", buflen); + return strscpy(buf, "(null)", buflen); - return strlcpy(buf, kn->parent ? kn->name : "/", buflen); + return strscpy(buf, kn->parent ? kn->name : "/", buflen); } /* kernfs_node_depth - compute depth from @from to @to */ @@ -182,12 +182,12 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, * @buflen: size of @buf * * Copies the name of @kn into @buf of @buflen bytes. The behavior is - * similar to strlcpy(). + * similar to strscpy(). * * Fills buffer with "(null)" if @kn is %NULL. * - * Return: the length of @kn's name and if @buf isn't long enough, - * it's filled up to @buflen-1 and nul terminated. + * Return: the resulting length of @buf. If @buf isn't long enough, + * it's filled up to @buflen-1 and nul terminated, and returns -E2BIG. * * This function can be called from any context. */