Re: [PATCH 1/2] Revert "lib: string: Fix strlcpy return value", fix callers

[Sean Anderson <sean.anderson@seco.com>]

On 7/14/23 07:24, Matthias Schiffer wrote:
> Both the Linux kernel and libbsd agree that strlcpy() should always
> return strlen(src) and not include the NUL termination. The incorrect
> U-Boot implementation makes it impossible to check the return value for
> truncation, and breaks code written with the usual implementation in
> mind (for example, fdtdec_add_reserved_memory() was subtly broken).
> 
> I reviewed all callers of strlcpy() and strlcat() and fixed them
> according to my understanding of the intended function.
> 
> This reverts commit d3358ecc54be0bc3b4dd11f7a63eab0a2842f772 and adds
> related fixes.
> 
> Fixes: d3358ecc54be ("lib: string: Fix strlcpy return value")
> Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> ---
>  board/amlogic/vim3/vim3.c    |  6 +++---
>  drivers/fastboot/fb_getvar.c |  2 +-
>  lib/string.c                 | 14 +++++++-------
>  test/lib/strlcat.c           |  4 ++--
>  4 files changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/board/amlogic/vim3/vim3.c b/board/amlogic/vim3/vim3.c
> index fcd60ab1e05..8bdfb302f72 100644
> --- a/board/amlogic/vim3/vim3.c
> +++ b/board/amlogic/vim3/vim3.c
> @@ -104,8 +104,8 @@ int meson_ft_board_setup(void *blob, struct bd_info *bd)
>  		}
>  
>  		/* Update PHY names (mandatory to disable USB3.0) */
> -		len = strlcpy(data, "usb2-phy0", 32);
> -		len += strlcpy(&data[len], "usb2-phy1", 32 - len);
> +		len = strlcpy(data, "usb2-phy0", 32) + 1;
> +		len += strlcpy(&data[len], "usb2-phy1", 32 - len) + 1;
>  		ret = fdt_setprop(blob, node, "phy-names", data, len);
>  		if (ret < 0) {
>  			printf("vim3: failed to update usb phy names property (%d)\n", ret);
> @@ -132,7 +132,7 @@ int meson_ft_board_setup(void *blob, struct bd_info *bd)
>  		}
>  
>  		/* Enable PCIe */
> -		len = strlcpy(data, "okay", 32);
> +		len = strlcpy(data, "okay", 32) + 1;
>  		ret = fdt_setprop(blob, node, "status", data, len);
>  		if (ret < 0) {
>  			printf("vim3: failed to enable pcie node (%d)\n", ret);
> diff --git a/drivers/fastboot/fb_getvar.c b/drivers/fastboot/fb_getvar.c
> index dd3475e0a8b..d9f0f07b2bc 100644
> --- a/drivers/fastboot/fb_getvar.c
> +++ b/drivers/fastboot/fb_getvar.c
> @@ -183,7 +183,7 @@ static void __maybe_unused getvar_has_slot(char *part_name, char *response)
>  
>  	/* part_name_wslot = part_name + "_a" */
>  	len = strlcpy(part_name_wslot, part_name, PART_NAME_LEN - 3);
> -	if (len > PART_NAME_LEN - 3)
> +	if (len >= PART_NAME_LEN - 3)
>  		goto fail;
>  	strcat(part_name_wslot, "_a");
>  
> diff --git a/lib/string.c b/lib/string.c
> index ecea755f405..f2c61471288 100644
> --- a/lib/string.c
> +++ b/lib/string.c
> @@ -116,20 +116,18 @@ char * strncpy(char * dest,const char *src,size_t count)
>   * of course, the buffer size is zero). It does not pad
>   * out the result like strncpy() does.
>   *
> - * Return: the number of bytes copied
> + * Return: strlen(src)
>   */
>  size_t strlcpy(char *dest, const char *src, size_t size)
>  {
> -	if (size) {
> -		size_t srclen = strlen(src);
> -		size_t len = (srclen >= size) ? size - 1 : srclen;
> +	size_t ret = strlen(src);
>  
> +	if (size) {
> +		size_t len = (ret >= size) ? size - 1 : ret;
>  		memcpy(dest, src, len);
>  		dest[len] = '\0';
> -		return len + 1;
>  	}
> -
> -	return 0;
> +	return ret;
>  }
>  #endif
>  
> @@ -191,6 +189,8 @@ char * strncat(char *dest, const char *src, size_t count)
>   * Compatible with *BSD: the result is always a valid NUL-terminated string that
>   * fits in the buffer (unless, of course, the buffer size is zero). It does not
>   * write past @size like strncat() does.
> + *
> + * Return: min(strlen(dest), size) + strlen(src)
>   */
>  size_t strlcat(char *dest, const char *src, size_t size)
>  {
> diff --git a/test/lib/strlcat.c b/test/lib/strlcat.c
> index a0ec037388b..d8453fe78e2 100644
> --- a/test/lib/strlcat.c
> +++ b/test/lib/strlcat.c
> @@ -43,11 +43,11 @@ static int do_test_strlcat(struct unit_test_state *uts, int line, size_t align1,
>  		s2[i] = 32 + 23 * i % (127 - 32);
>  	s2[len2 - 1] = '\0';
>  
> -	expected = len2 < n ? min(len1 + len2 - 1, n) : n;
> +	expected = min(strlen(s2), n) + strlen(s1);
>  	actual = strlcat(s2, s1, n);
>  	if (expected != actual) {
>  		ut_failf(uts, __FILE__, line, __func__,
> -			 "strlcat(s2, s1, 2) == len2 < n ? min(len1 + len2, n) : n",
> +			 "strlcat(s2, s1, n) == min(len2, n) + len1",
>  			 "Expected %#zx (%zd), got %#zx (%zd)",
>  			 expected, expected, actual, actual);
>  		return CMD_RET_FAILURE;

I remembered that something was off with this patch, but I never went
back to fix it...

Reviewed-by: Sean Anderson <sean.anderson@seco.com>