Re: [PATCH] EDAC, thunderx: fix possible out-of-bounds string access.

[Borislav Petkov]

On Wed, Nov 22, 2023 at 11:19:53PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
> 
> Commit 1b56c90018f0 ("Makefile: Enable -Wstringop-overflow globally") exposes a
> warning for a common bug in the usage of strncat():
> 
> drivers/edac/thunderx_edac.c: In function 'thunderx_ocx_com_threaded_isr':
> drivers/edac/thunderx_edac.c:1136:17: error: 'strncat' specified bound 1024 equals destination size [-Werror=stringop-overflow=]
>  1136 |                 strncat(msg, other, OCX_MESSAGE_SIZE);
>       |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/edac/thunderx_edac.c:1145:33: error: 'strncat' specified bound 1024 equals destination size [-Werror=stringop-overflow=]
>  1145 |                                 strncat(msg, other, OCX_MESSAGE_SIZE);
>       |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/edac/thunderx_edac.c:1150:33: error: 'strncat' specified bound 1024 equals destination size [-Werror=stringop-overflow=]
>  1150 |                                 strncat(msg, other, OCX_MESSAGE_SIZE);
>       |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/edac/thunderx_edac.c: In function 'thunderx_l2c_threaded_isr':
> drivers/edac/thunderx_edac.c:1899:17: error: 'strncat' specified bound 1024 equals destination size [-Werror=stringop-overflow=]
>  1899 |                 strncat(msg, other, L2C_MESSAGE_SIZE);
>       |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/edac/thunderx_edac.c: In function 'thunderx_ocx_lnk_threaded_isr':
> drivers/edac/thunderx_edac.c:1220:17: error: 'strncat' specified bound 1024 equals destination size [-Werror=stringop-overflow=]
>  1220 |                 strncat(msg, other, OCX_MESSAGE_SIZE);
>       |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Apparently the author of this driver expected strncat() to behave the
> way that strlcat() does, which uses the size of the destination buffer
> as its third argument rather than the length of the source buffer.
> The result is that there is no check on the size of the allocated
> buffer.
> 
> Change it to use strncat().
> 
> Fixes: 41003396f932 ("EDAC, thunderx: Add Cavium ThunderX EDAC driver")
> Cc: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
>  drivers/edac/thunderx_edac.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)

Applied, thanks.

-- 
Regards/Gruss,
    Boris.

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