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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id t14-20020a63eb0e000000b005ac384b71cbsm8583878pgh.60.2023.12.12.13.17.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Dec 2023 13:17:41 -0800 (PST) From: Kees Cook To: Greg Kroah-Hartman Cc: Kees Cook , Tejun Heo , Azeem Shaikh , Zefan Li , Johannes Weiner , Waiman Long , Christophe JAILLET , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, bpf@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v3 1/3] kernfs: Convert kernfs_walk_ns() from strlcpy() to strscpy() Date: Tue, 12 Dec 2023 13:17:38 -0800 Message-Id: <20231212211741.164376-1-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231212211606.make.155-kees@kernel.org> References: <20231212211606.make.155-kees@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1627; i=keescook@chromium.org; h=from:subject; bh=KaMikVVf9IlMYxhWSymwvYJ80Grx9jhkkXD92Gcwols=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBleM3zg8fq+Kgz91M5MgN0iGKTEy9c1pTW6k2g3 Om7gwyq3vSJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZXjN8wAKCRCJcvTf3G3A JiEbD/9sPG6e4XUmGL/t2yQxqs/Tot72LHnqAm/mN/d6Ly5AAAqHsoFvek/mQG8wTg0lCNknNj1 YF1q7adAapgFepvZU8OXC+tWuPzPLcG3o8K6Sgkeir5yl9fwIzvjt/J0dJZoYYENLHghz4BAKXi rzcIQJGt+KoQ1kgGjloXVMlL9LG0DZtXjSoBCd9a5u77yL2JMD/XxJt/ttDsxn52o+ts7JLolAo YKyCkIpgJbBrALTTmUjiOCIh1UJzxnQFkN2EtES96fjl+CVDIg/8tmBk5AZZDTh66MQ75dbLi6I +1n+T71e3pcJDw97P1Hfd7QmLBAQSSNgTD8DemX7IVA52zA01seskFB9mwF/8GYRzvm1TJisAqM PeNcVIyvLDfy1ahMBfJszaBkCqnOmmwjVGfSLGhtq93fVgtjaD4zfyP0UtsNFTVVbjQ9tU84hev 7dd6XddCX4RE6UvGt8qoPYZRUlkfb84C+zWvymEA2Gn/eaq8y5odSWRlXl3WFPW3XDvilS4fER6 qrMi85l+bsuNtfTSIwl/x6YCRX3j3zmPwmaI6n8VA3xjMNARhArAAAdpCpG2TjocSWY1ZOID5OX xUkJTCaX7P1h/qoC1gVn2OIdWrbRnbsAXSNrAplbX1sBjWSnBCAUqNNmxw93lDSSn/pSyBZGigO UaMJYSmjnQJhdiw== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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(). Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcp= y [1] Link: https://github.com/KSPP/linux/issues/89 [2] Cc: Greg Kroah-Hartman Cc: Tejun Heo Cc: Azeem Shaikh Link: https://lore.kernel.org/r/20231116192127.1558276-1-keescook@chromium.= org Signed-off-by: Kees Cook Acked-by: Tejun Heo --- fs/kernfs/dir.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 8b2bd65d70e7..37353901ede1 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -850,16 +850,16 @@ static struct kernfs_node *kernfs_walk_ns(struct kern= fs_node *parent, const unsigned char *path, const void *ns) { - size_t len; + ssize_t len; char *p, *name; =20 lockdep_assert_held_read(&kernfs_root(parent)->kernfs_rwsem); =20 spin_lock_irq(&kernfs_pr_cont_lock); =20 - len =3D strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); + len =3D strscpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); =20 - if (len >=3D sizeof(kernfs_pr_cont_buf)) { + if (len < 0) { spin_unlock_irq(&kernfs_pr_cont_lock); return NULL; } --=20 2.34.1