Commit 899537b7 authored Apr 15, 2019 by Gustavo A. R. Silva Committed by David S. Miller Apr 16, 2019

net: atm: Fix potential Spectre v1 vulnerabilities

arg is controlled by user-space, hence leading to a potential
exploitation of the Spectre variant 1 vulnerability.

This issue was detected with the help of Smatch:

net/atm/lec.c:715 lec_mcast_attach() warn: potential spectre issue 'dev_lec' [r] (local cap)

Fix this by sanitizing arg before using it to index dev_lec.

Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].

[1] https://lore.kernel.org/lkml/20180423164740.GY17484@dhcp22.suse.cz/



Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent ad910c7c

net/atm/lec.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -710,7 +710,10 @@ static int lec_vcc_attach(struct atm_vcc vcc, void __user arg)

		static int lec_mcast_attach(struct atm_vcc *vcc, int arg)
		{
		if (arg < 0 \|\| arg >= MAX_LEC_ITF \|\| !dev_lec[arg])
		if (arg < 0 \|\| arg >= MAX_LEC_ITF)
		return -EINVAL;
		arg = array_index_nospec(arg, MAX_LEC_ITF);
		if (!dev_lec[arg])
		return -EINVAL;
		vcc->proto_data = dev_lec[arg];
		return lec_mcast_make(netdev_priv(dev_lec[arg]), vcc);
		@@ -728,6 +731,7 @@ static int lecd_attach(struct atm_vcc *vcc, int arg)
		i = arg;
		if (arg >= MAX_LEC_ITF)
		return -EINVAL;
		i = array_index_nospec(arg, MAX_LEC_ITF);
		if (!dev_lec[i]) {
		int size;

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