Revision 99f62a746066fa436aa15d4606a538569540db08 authored by Vladimir Oltean on 21 September 2020, 22:07:09 UTC, committed by David S. Miller on 22 September 2020, 00:37:44 UTC
When calling the RCU brother of br_vlan_get_pvid(), lockdep warns:
=============================
WARNING: suspicious RCU usage
5.9.0-rc3-01631-g13c17acb8e38-dirty #814 Not tainted
-----------------------------
net/bridge/br_private.h:1054 suspicious rcu_dereference_protected() usage!
Call trace:
lockdep_rcu_suspicious+0xd4/0xf8
__br_vlan_get_pvid+0xc0/0x100
br_vlan_get_pvid_rcu+0x78/0x108
The warning is because br_vlan_get_pvid_rcu() calls nbp_vlan_group()
which calls rtnl_dereference() instead of rcu_dereference(). In turn,
rtnl_dereference() calls rcu_dereference_protected() which assumes
operation under an RCU write-side critical section, which obviously is
not the case here. So, when the incorrect primitive is used to access
the RCU-protected VLAN group pointer, READ_ONCE() is not used, which may
cause various unexpected problems.
I'm sad to say that br_vlan_get_pvid() and br_vlan_get_pvid_rcu() cannot
share the same implementation. So fix the bug by splitting the 2
functions, and making br_vlan_get_pvid_rcu() retrieve the VLAN groups
under proper locking annotations.
Fixes: 7582f5b70f9a ("bridge: add br_vlan_get_pvid_rcu()")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent 47cec3f
net_utils.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/string.h>
#include <linux/if_ether.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
bool mac_pton(const char *s, u8 *mac)
{
int i;
/* XX:XX:XX:XX:XX:XX */
if (strlen(s) < 3 * ETH_ALEN - 1)
return false;
/* Don't dirty result unless string is valid MAC. */
for (i = 0; i < ETH_ALEN; i++) {
if (!isxdigit(s[i * 3]) || !isxdigit(s[i * 3 + 1]))
return false;
if (i != ETH_ALEN - 1 && s[i * 3 + 2] != ':')
return false;
}
for (i = 0; i < ETH_ALEN; i++) {
mac[i] = (hex_to_bin(s[i * 3]) << 4) | hex_to_bin(s[i * 3 + 1]);
}
return true;
}
EXPORT_SYMBOL(mac_pton);
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