linux-kernel - [PATCH 04/20] dma-buf: Manual replacement of the deprecated strlcpy() with return values

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Message-Id: <20210222151231.22572-5-romain.perier@gmail.com>
Date:   Mon, 22 Feb 2021 16:12:15 +0100
From:   Romain Perier <romain.perier@...il.com>
To:     Kees Cook <keescook@...omium.org>,
        kernel-hardening@...ts.openwall.com,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>
Cc:     Romain Perier <romain.perier@...il.com>,
        linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linaro-mm-sig@...ts.linaro.org, linux-kernel@...r.kernel.org
Subject: [PATCH 04/20] dma-buf: Manual replacement of the deprecated strlcpy() with return values

The strlcpy() reads the entire source buffer first, it is dangerous if
the source buffer lenght is unbounded or possibility non NULL-terminated.
It can lead to linear read overflows, crashes, etc...

As recommended in the deprecated interfaces [1], it should be replaced
by strscpy.

This commit replaces all calls to strlcpy that handle the return values
by the corresponding strscpy calls with new handling of the return
values (as it is quite different between the two functions).

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy

Signed-off-by: Romain Perier <romain.perier@...il.com>
---
 drivers/dma-buf/dma-buf.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index f264b70c383e..515192f2f404 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -42,12 +42,12 @@ static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
 {
 	struct dma_buf *dmabuf;
 	char name[DMA_BUF_NAME_LEN];
-	size_t ret = 0;
+	ssize_t ret = 0;
 
 	dmabuf = dentry->d_fsdata;
 	spin_lock(&dmabuf->name_lock);
 	if (dmabuf->name)
-		ret = strlcpy(name, dmabuf->name, DMA_BUF_NAME_LEN);
+		ret = strscpy(name, dmabuf->name, DMA_BUF_NAME_LEN);
 	spin_unlock(&dmabuf->name_lock);
 
 	return dynamic_dname(dentry, buffer, buflen, "/%s:%s",