Re: [PATCH][UML] Boot broken due to buffer overrun

[Pekka Enberg]

Hi Balbir,

On Sat, Nov 29, 2008 at 12:08 PM, Balbir Singh
<balbir@xxxxxxxxxxxxxxxxxx> wrote:
> mconsole_init() passed 256 bytes as length in os_create_unix_socket, while
> the sizeof UNIX_PATH_MAX is 108. This patch fixes that problem and avoids
> a big overrun bug reported on UML bootup.

Maybe mention that ->sun_path in struct sockaddr_un is UNIX_PATH_MAX
long which causes the problem?

> Reported-by: Vikas K Managutte <vikki.km@xxxxxxxxx>
> Reported-by: Sarvesh Kumar Lal Das <skldas@xxxxxxxxx>
> Signed-off-by: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>

Reviewed-by: Pekka Enberg <penberg@xxxxxxxxxxxxxx>

> ---
>
>  arch/um/drivers/mconsole_kern.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff -puN arch/um/drivers/mconsole_kern.c~fix-uml-buggy-socket-creation arch/um/drivers/mconsole_kern.c
> --- linux-2.6.28-rc6/arch/um/drivers/mconsole_kern.c~fix-uml-buggy-socket-creation      2008-11-29 15:29:04.000000000 +0530
> +++ linux-2.6.28-rc6-balbir/arch/um/drivers/mconsole_kern.c     2008-11-29 15:32:23.000000000 +0530
> @@ -16,6 +16,8 @@
>  #include <linux/slab.h>
>  #include <linux/syscalls.h>
>  #include <linux/utsname.h>
> +#include <linux/socket.h>
> +#include <linux/un.h>
>  #include <linux/workqueue.h>
>  #include <linux/mutex.h>
>  #include <asm/uaccess.h>
> @@ -785,7 +787,7 @@ static int __init mconsole_init(void)
>        /* long to avoid size mismatch warnings from gcc */
>        long sock;
>        int err;
> -       char file[256];
> +       char file[UNIX_PATH_MAX];
>
>        if (umid_file_name("mconsole", file, sizeof(file)))
>                return -1;
> _
>
> --
>        Balbir
> --
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