Commit 8d390efd authored Apr 24, 2008 by Tom Quetchenbach Committed by David S. Miller Apr 24, 2008

tcp: tcp_probe buffer overflow and incorrect return value



tcp_probe has a bounds-checking bug that causes many programs (less,
python) to crash reading /proc/net/tcp_probe. When it outputs a log
line to the reader, it only checks if that line alone will fit in the
reader's buffer, rather than that line and all the previous lines it
has already written.

tcpprobe_read also returns the wrong value if copy_to_user fails--it
just passes on the return value of copy_to_user (number of bytes not
copied), which makes a failure look like a success.

This patch fixes the buffer overflow and sets the return value to
-EFAULT if copy_to_user fails.

Patch is against latest net-2.6; tested briefly and seems to fix the
crashes in less and python.

Signed-off-by: Tom Quetchenbach <virtualphtn@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent a5d6ab56

net/ipv4/tcp_probe.c

+4 −5

Original line number	Original line	Diff line number	Diff line
	@@ -190,19 +190,18 @@ static ssize_t tcpprobe_read(struct file file, char __user buf,

	width = tcpprobe_sprint(tbuf, sizeof(tbuf));		width = tcpprobe_sprint(tbuf, sizeof(tbuf));

	if (width < len)		if (cnt + width < len)
	tcp_probe.tail = (tcp_probe.tail + 1) % bufsize;		tcp_probe.tail = (tcp_probe.tail + 1) % bufsize;

	spin_unlock_bh(&tcp_probe.lock);		spin_unlock_bh(&tcp_probe.lock);

	/* if record greater than space available		/* if record greater than space available
	return partial buffer (so far) */		return partial buffer (so far) */
	if (width >= len)		if (cnt + width >= len)
	break;		break;

	error = copy_to_user(buf + cnt, tbuf, width);		if (copy_to_user(buf + cnt, tbuf, width))
	if (error)		return -EFAULT;
	break;
	cnt += width;		cnt += width;
	}		}