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From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date: Mon, 22 Jan 2024 13:27:46 -0500
Message-ID: <CABBYNZKW8odyLb_BQcXXpjAKjPzHRhXVCbxvcg54VkoeULeHnw@mail.gmail.com>
Subject: Re: [PATCH BlueZ] btmon-logger: Fix stack corruption
To: =?UTF-8?Q?Mariusz_Koz=C5=82owski?= <mk@lab.zgora.pl>
Cc: linux-bluetooth@vger.kernel.org
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Hi Mariusz,

On Sun, Jan 21, 2024 at 5:04=E2=80=AFAM Mariusz Koz=C5=82owski <mk@lab.zgor=
a.pl> wrote:
>
> Version 3 capability masks are 64 bits in size.
> ---
>  tools/btmon-logger.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/tools/btmon-logger.c b/tools/btmon-logger.c
> index a770ad575..1f6db3751 100644
> --- a/tools/btmon-logger.c
> +++ b/tools/btmon-logger.c
> @@ -161,14 +161,14 @@ extern int capset(struct __user_cap_header_struct *=
header,
>  static void drop_capabilities(void)
>  {
>         struct __user_cap_header_struct header;
> -       struct __user_cap_data_struct cap;
> +       struct __user_cap_data_struct cap[_LINUX_CAPABILITY_U32S_3];

Ok, but this doesn't change the field, it makes it an array, or are
you talking about the following note:

Note that 64-bit capabilities use datap[0] and datap[1], whereas
32-bit capabilities use only datap[0].

In that case Ive just pointed out to this note to explain why this is neede=
d.

>         unsigned int mask;
>         int err;
>
>         header.version =3D _LINUX_CAPABILITY_VERSION_3;
>         header.pid =3D 0;
>
> -       err =3D capget(&header, &cap);
> +       err =3D capget(&header, cap);
>         if (err) {
>                 perror("Unable to get current capabilities");
>                 return;
> @@ -177,11 +177,11 @@ static void drop_capabilities(void)
>         /* not needed anymore since monitor socket is already open */
>         mask =3D ~CAP_TO_MASK(CAP_NET_RAW);
>
> -       cap.effective &=3D mask;
> -       cap.permitted &=3D mask;
> -       cap.inheritable &=3D mask;
> +       cap[0].effective &=3D mask;
> +       cap[0].permitted &=3D mask;
> +       cap[0].inheritable &=3D mask;
>
> -       err =3D capset(&header, &cap);
> +       err =3D capset(&header, cap);
>         if (err)
>                 perror("Failed to set capabilities");
>  }
> --
> 2.34.1
>
>


--=20
Luiz Augusto von Dentz