On Thu, Aug 10, 2023 at 03:12:42PM -0400, Sishuai Gong wrote: + Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> Florian Westphal <fw@xxxxxxxxx> Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxx> netfilter-devel@xxxxxxxxxxxxxxx coreteam@xxxxxxxxxxxxx > When two threads run proc_do_sync_threshold() in parallel, > data races could happen between the two memcpy(): > > Thread-1 Thread-2 > memcpy(val, valp, sizeof(val)); > memcpy(valp, val, sizeof(val)); > > This race might mess up the (struct ctl_table *) table->data, > so we add a mutex lock to serilize them, as discussed in [1]. > > [1] https://archive.linuxvirtualserver.org/html/lvs-devel/2023-08/msg00031.html > > Signed-off-by: Sishuai Gong <sishuai.system@xxxxxxxxx> Probably this is a fix for nf and should have: Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") In any case, this change looks good to me. Acked-by: Simon Horman <horms@xxxxxxxxxx> > --- > net/netfilter/ipvs/ip_vs_ctl.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c > index 62606fb44d02..4bb0d90eca1c 100644 > --- a/net/netfilter/ipvs/ip_vs_ctl.c > +++ b/net/netfilter/ipvs/ip_vs_ctl.c > @@ -1876,6 +1876,7 @@ static int > proc_do_sync_threshold(struct ctl_table *table, int write, > void *buffer, size_t *lenp, loff_t *ppos) > { > + struct netns_ipvs *ipvs = table->extra2; > int *valp = table->data; > int val[2]; > int rc; > @@ -1885,6 +1886,7 @@ proc_do_sync_threshold(struct ctl_table *table, int write, > .mode = table->mode, > }; > > + mutex_lock(&ipvs->sync_mutex); > memcpy(val, valp, sizeof(val)); > rc = proc_dointvec(&tmp, write, buffer, lenp, ppos); > if (write) { > @@ -1894,6 +1896,7 @@ proc_do_sync_threshold(struct ctl_table *table, int write, > else > memcpy(valp, val, sizeof(val)); > } > + mutex_unlock(&ipvs->sync_mutex); > return rc; > } > > @@ -4321,6 +4324,7 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs) > ipvs->sysctl_sync_threshold[0] = DEFAULT_SYNC_THRESHOLD; > ipvs->sysctl_sync_threshold[1] = DEFAULT_SYNC_PERIOD; > tbl[idx].data = &ipvs->sysctl_sync_threshold; > + tbl[idx].extra2 = ipvs; > tbl[idx++].maxlen = sizeof(ipvs->sysctl_sync_threshold); > ipvs->sysctl_sync_refresh_period = DEFAULT_SYNC_REFRESH_PERIOD; > tbl[idx++].data = &ipvs->sysctl_sync_refresh_period; > -- > 2.39.2 (Apple Git-143) >
