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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>,
	netdev@vger.kernel.org, jon.maloy@ericsson.com,
	allan.stephens@windriver.com,
	Dan Rosenberg <drosenberg@vsecurity.com>
Subject: Re: [PATCH] net: Limit socket I/O iovec total length to INT_MAX.
Date: Fri, 29 Oct 2010 17:45:32 +0100	[thread overview]
Message-ID: <20101029164532.GV19804@ZenIV.linux.org.uk> (raw)
In-Reply-To: <AANLkTi=sUDRzGnkp57OCQUi9APHWLYLShhiTVHLyq1eV@mail.gmail.com>

On Fri, Oct 29, 2010 at 09:21:16AM -0700, Linus Torvalds wrote:
>  	ret = -EINVAL;
>  	for (seg = 0; seg < nr_segs; seg++) {
> -		compat_ssize_t tmp = tot_len;
>  		compat_uptr_t buf;
>  		compat_ssize_t len;
>  
> @@ -624,13 +624,13 @@ ssize_t compat_rw_copy_check_uvector(int type,
>  		}
>  		if (len < 0)	/* size_t not fitting in compat_ssize_t .. */
>  			goto out;
> -		tot_len += len;
> -		if (tot_len < tmp) /* maths overflow on the compat_ssize_t */
> -			goto out;
>  		if (!access_ok(vrfy_dir(type), compat_ptr(buf), len)) {
>  			ret = -EFAULT;
>  			goto out;
>  		}
> +		if (len > MAX_RW_COUNT - tot_len)
> +			len = MAX_RW_COUNT - tot_len;
> +		tot_len += len;
>  		iov->iov_base = compat_ptr(buf);
>  		iov->iov_len = (compat_size_t) len;
>  		uvector++;

Interesting...  Had anybody tested vectors with 0 iov_len in the end and/or
middle?  Looks like something rarely hit in practice...

I don't see anything obviously broken (and we obviously have allowed
iov_len == 0 cases all along, so if anything, breakage won't be new).
However, I wonder if things like sendmsg() for datagrams have warranties
against silent truncation.  Davem?

  reply	other threads:[~2010-10-29 16:45 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-28 18:22 [PATCH] net: Limit socket I/O iovec total length to INT_MAX David Miller
2010-10-28 18:33 ` Linus Torvalds
2010-10-28 18:37   ` David Miller
2010-10-29  6:40 ` Linus Torvalds
2010-10-29 14:00   ` Dan Rosenberg
2010-10-29 15:28     ` Linus Torvalds
2010-10-29 16:21       ` Linus Torvalds
2010-10-29 16:45         ` Al Viro [this message]
2010-10-29 17:01           ` Linus Torvalds
2010-10-29 17:32             ` Al Viro
2010-10-29 19:32         ` David Miller
2010-10-29 19:37           ` Linus Torvalds
2010-10-29 19:55             ` David Miller
2010-10-29 20:22               ` Dan Rosenberg
2010-10-29 18:51       ` Rick Jones
2010-10-29 18:59         ` Linus Torvalds

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