4.14-stable review patch. If anyone has any objections, please let me know.
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From: Alex Henrie alexhenrie24@gmail.com
[ Upstream commit f31867d0d9d82af757c1e0178b659438f4c1ea3c ]
The existing code incorrectly casted a negative value (the result of a subtraction) to an unsigned value without checking. For example, if /proc/sys/net/ipv6/conf/*/temp_prefered_lft was set to 1, the preferred lifetime would jump to 4 billion seconds. On my machine and network the shortest lifetime that avoided underflow was 3 seconds.
Fixes: 76506a986dc3 ("IPv6: fix DESYNC_FACTOR") Signed-off-by: Alex Henrie alexhenrie24@gmail.com Reviewed-by: David Ahern dsahern@kernel.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/addrconf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 893b93cc5221a..288e270bd0176 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -1283,7 +1283,7 @@ static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp, struct inet6_ifaddr *i * idev->desync_factor if it's larger */ cnf_temp_preferred_lft = READ_ONCE(idev->cnf.temp_prefered_lft); - max_desync_factor = min_t(__u32, + max_desync_factor = min_t(long, idev->cnf.max_desync_factor, cnf_temp_preferred_lft - regen_advance);