When writing to the forwarding sysctl, if proc_dointvec() fails to parse the input, it returns a negative error code. The current implementation is overwriting that error for write operations. This results in a silent failure, it returns a successful write although the configuration was not modified at all. When modifying the "all" variant it can also modify the configuration of existing interfaces to the wrong value. Fix this by checking the return value of proc_dointvec() and returning early on failure. In addition, adjust return code of addrconf_fixup_forwarding() for successful operation. Fixes: b325fddb7f86 ("ipv6: Fix sysctl unregistration deadlock") Reviewed-by: Nicolas Dichtel Signed-off-by: Fernando Fernandez Mancera --- net/ipv6/addrconf.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 70058d971205..d23a89b07eed 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -913,7 +913,7 @@ static int addrconf_fixup_forwarding(const struct ctl_table *table, int *p, int if (newf) rt6_purge_dflt_routers(net); - return 1; + return 0; } static void addrconf_linkdown_change(struct net *net, __s32 newf) @@ -6370,6 +6370,8 @@ static int addrconf_sysctl_forward(const struct ctl_table *ctl, int write, lctl.data = &val; ret = proc_dointvec(&lctl, write, buffer, lenp, ppos); + if (ret) + return ret; if (write) ret = addrconf_fixup_forwarding(ctl, valp, val); -- 2.54.0