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authorYOSHIFUJI Hideaki / 吉藤英明 <yoshfuji@linux-ipv6.org>2013-02-20 00:29:08 +0000
committerDavid S. Miller <davem@davemloft.net>2013-02-20 15:11:45 -0500
commitecd9883724b78cc72ed92c98bcb1a46c764fff21 (patch)
treec18d4c96f7e4dcf278c88e505be8225af7374800 /arch/alpha/kernel/osf_sys.c
parent68534c682e8f5c333f835818ca5a89d3e6288870 (diff)
downloadlinux-stericsson-ecd9883724b78cc72ed92c98bcb1a46c764fff21.tar.gz
ipv6: fix race condition regarding dst->expires and dst->from.
Eric Dumazet wrote: | Some strange crashes happen in rt6_check_expired(), with access | to random addresses. | | At first glance, it looks like the RTF_EXPIRES and | stuff added in commit 1716a96101c49186b | (ipv6: fix problem with expired dst cache) | are racy : same dst could be manipulated at the same time | on different cpus. | | At some point, our stack believes rt->dst.from contains a dst pointer, | while its really a jiffie value (as rt->dst.expires shares the same area | of memory) | | rt6_update_expires() should be fixed, or am I missing something ? | | CC Neil because of https://bugzilla.redhat.com/show_bug.cgi?id=892060 Because we do not have any locks for dst_entry, we cannot change essential structure in the entry; e.g., we cannot change reference to other entity. To fix this issue, split 'from' and 'expires' field in dst_entry out of union. Once it is 'from' is assigned in the constructor, keep the reference until the very last stage of the life time of the object. Of course, it is unsafe to change 'from', so make rt6_set_from simple just for fresh entries. Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Reported-by: Neil Horman <nhorman@tuxdriver.com> CC: Gao Feng <gaofeng@cn.fujitsu.com> Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Reviewed-by: Eric Dumazet <edumazet@google.com> Reported-by: Steinar H. Gunderson <sesse@google.com> Reviewed-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/alpha/kernel/osf_sys.c')
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