dma-buf: Replace strlcpy() with strscpy()

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#strlcpy
Link: https://github.com/KSPP/linux/issues/89
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: Azeem Shaikh <azeemshaikh38@gmail.com>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231116191409.work.634-kees@kernel.org
Signed-off-by: Christian König <christian.koenig@amd.com>

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 21916bba77d58be342d2d82dc654c7df330f01fb..8fe5aa67b16783d3df94ea0250022d745a74bc3d 100644 (file)
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -46,12 +46,12 @@ 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, sizeof(name));
        spin_unlock(&dmabuf->name_lock);
 
        return dynamic_dname(buffer, buflen, "/%s:%s",