2021-09-06 13:55:23

by Jason Wang

[permalink] [raw]
Subject: [PATCH] MIPS: BCM47XX: Replace strlcpy with strscpy

The strlcpy should not be used because it doesn't limit the source
length. As linus says, it's a completely useless function if you
can't implicitly trust the source string - but that is almost always
why people think they should use it! All in all the BSD function
will lead some potential bugs.

But the strscpy doesn't require reading memory from the src string
beyond the specified "count" bytes, and since the return value is
easier to error-check than strlcpy()'s. In addition, the implementation
is robust to the string changing out from underneath it, unlike the
current strlcpy() implementation.

Thus, We prefer using strscpy instead of strlcpy.

Signed-off-by: Jason Wang <[email protected]>
---
arch/mips/bcm47xx/board.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/bcm47xx/board.c b/arch/mips/bcm47xx/board.c
index 35266a70e22a..74113dcd86e0 100644
--- a/arch/mips/bcm47xx/board.c
+++ b/arch/mips/bcm47xx/board.c
@@ -345,7 +345,7 @@ void __init bcm47xx_board_detect(void)

board_detected = bcm47xx_board_get_nvram();
bcm47xx_board.board = board_detected->board;
- strlcpy(bcm47xx_board.name, board_detected->name,
+ strscpy(bcm47xx_board.name, board_detected->name,
BCM47XX_BOARD_MAX_NAME);
}

--
2.33.0


2021-12-16 15:08:00

by Thomas Bogendoerfer

[permalink] [raw]
Subject: Re: [PATCH] MIPS: BCM47XX: Replace strlcpy with strscpy

On Mon, Sep 06, 2021 at 09:49:23PM +0800, Jason Wang wrote:
> The strlcpy should not be used because it doesn't limit the source
> length. As linus says, it's a completely useless function if you
> can't implicitly trust the source string - but that is almost always
> why people think they should use it! All in all the BSD function
> will lead some potential bugs.
>
> But the strscpy doesn't require reading memory from the src string
> beyond the specified "count" bytes, and since the return value is
> easier to error-check than strlcpy()'s. In addition, the implementation
> is robust to the string changing out from underneath it, unlike the
> current strlcpy() implementation.
>
> Thus, We prefer using strscpy instead of strlcpy.
>
> Signed-off-by: Jason Wang <[email protected]>
> ---
> arch/mips/bcm47xx/board.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/bcm47xx/board.c b/arch/mips/bcm47xx/board.c
> index 35266a70e22a..74113dcd86e0 100644
> --- a/arch/mips/bcm47xx/board.c
> +++ b/arch/mips/bcm47xx/board.c
> @@ -345,7 +345,7 @@ void __init bcm47xx_board_detect(void)
>
> board_detected = bcm47xx_board_get_nvram();
> bcm47xx_board.board = board_detected->board;
> - strlcpy(bcm47xx_board.name, board_detected->name,
> + strscpy(bcm47xx_board.name, board_detected->name,
> BCM47XX_BOARD_MAX_NAME);
> }
>
> --
> 2.33.0

applied to mips-next.

Thomas.

--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]