From: Nicolas Dichtel <nicolas.dichtel@6wind.com> stable inclusion from stable-v5.10.142 commit 685f4e56717edb02d35fa2ae65b2fa40c8ed12e4 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6CSFH Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit eb55dc09b5dd040232d5de32812cc83001a23da6 upstream. __mkroute_input() uses fib_validate_source() to trigger an icmp redirect. My understanding is that fib_validate_source() is used to know if the src address and the gateway address are on the same link. For that, fib_validate_source() returns 1 (same link) or 0 (not the same network). __mkroute_input() is the only user of these positive values, all other callers only look if the returned value is negative. Since the below patch, fib_validate_source() didn't return anymore 1 when both addresses are on the same network, because the route lookup returns RT_SCOPE_LINK instead of RT_SCOPE_HOST. But this is, in fact, right. Let's adapat the test to return 1 again when both addresses are on the same link. CC: stable@vger.kernel.org Fixes: 747c14307214 ("ip: fix dflt addr selection for connected nexthop") Reported-by: kernel test robot <yujie.liu@intel.com> Reported-by: Heng Qi <hengqi@linux.alibaba.com> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Reviewed-by: David Ahern <dsahern@kernel.org> Link: https://lore.kernel.org/r/20220829100121.3821-1-nicolas.dichtel@6wind.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> Reviewed-by: Zheng Zengkai <zhengzengkai@huawei.com> --- net/ipv4/fib_frontend.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index 0df4594b49c7..af8a4255cf1b 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -389,7 +389,7 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst, dev_match = dev_match || (res.type == RTN_LOCAL && dev == net->loopback_dev); if (dev_match) { - ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_HOST; + ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_LINK; return ret; } if (no_addr) @@ -401,7 +401,7 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst, ret = 0; if (fib_lookup(net, &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE) == 0) { if (res.type == RTN_UNICAST) - ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_HOST; + ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_LINK; } return ret; -- 2.25.1