Commit 20b0c718 authored Feb 21, 2014 by Mathias Krause Committed by David S. Miller Feb 24, 2014

pktgen: fix out-of-bounds access in pgctrl_write()

If a privileged user writes an empty string to /proc/net/pktgen/pgctrl
the code for stripping the (then non-existent) '\n' actually writes the
zero byte at index -1 of data[]. The then still uninitialized array will
very likely fail the command matching tests and the pr_warning() at the
end will therefore leak stack bytes to the kernel log.

Fix those issues by simply ensuring we're passed a non-empty string as
the user API apparently expects a trailing '\n' for all commands.

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 8bfdfbc1

net/core/pktgen.c

+4 −1

Original line number	Original line	Diff line number	Diff line
	@@ -485,6 +485,9 @@ static ssize_t pgctrl_write(struct file file, const char __user buf,
	goto out;		goto out;
	}		}

			if (count == 0)
			return -EINVAL;

	if (count > sizeof(data))		if (count > sizeof(data))
	count = sizeof(data);		count = sizeof(data);

	@@ -492,7 +495,7 @@ static ssize_t pgctrl_write(struct file file, const char __user buf,
	err = -EFAULT;		err = -EFAULT;
	goto out;		goto out;
	}		}
	data[count - 1] = 0; /* Make string */		data[count - 1] = 0; /* Strip trailing '\n' and terminate string */

	if (!strcmp(data, "stop"))		if (!strcmp(data, "stop"))
	pktgen_stop_all_threads_ifs(pn);		pktgen_stop_all_threads_ifs(pn);