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Message-ID: <1343629340.2626.13268.camel@edumazet-glaptop>
Date: Mon, 30 Jul 2012 08:22:20 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: Mathias Krause <minipli@...glemail.com>
Cc: "David S. Miller" <davem@...emloft.net>,
richard -rw- weinberger <richard.weinberger@...il.com>,
netdev@...r.kernel.org
Subject: Re: [PATCH v2] net/tun: fix ioctl() based info leaks
On Mon, 2012-07-30 at 07:45 +0200, Mathias Krause wrote:
> The tun module leaks up to 36 bytes of memory by not fully initializing
> a structure located on the stack that gets copied to user memory by the
> TUNGETIFF and SIOCGIFHWADDR ioctl()s.
>
> Signed-off-by: Mathias Krause <minipli@...glemail.com>
> ---
> v2:
> - removed braces around else branch
> - minor adjustment of the commit message
>
> drivers/net/tun.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 987aeef..01255ff 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1252,9 +1252,11 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
> int vnet_hdr_sz;
> int ret;
>
> - if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89)
> + if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89) {
> if (copy_from_user(&ifr, argp, ifreq_len))
> return -EFAULT;
> + } else
> + memset(&ifr, 0, sizeof(ifr));
>
> if (cmd == TUNGETFEATURES) {
> /* Currently this just means: "what IFF flags are valid?".
Actually braces were better
vi +169 Documentation/CodingStyle
This does not apply if only one branch of a conditional statement is a
single
statement; in the latter case use braces in both branches:
if (condition) {
do_this();
do_that();
} else {
otherwise();
}
--
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