This is a note to let you know that I've just added the patch titled
neighbour: fix various data-races
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
neighbour-fix-various-data-races.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8fbf62904e406e112d817f8173caf187e60172a6
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Thu Oct 19 12:21:04 2023 +0000
neighbour: fix various data-races
[ Upstream commit a9beb7e81bcb876615e1fbb3c07f3f9dba69831f ]
1) tbl->gc_thresh1, tbl->gc_thresh2, tbl->gc_thresh3 and tbl->gc_interval
can be written from sysfs.
2) tbl->last_flush is read locklessly from neigh_alloc()
3) tbl->proxy_queue.qlen is read locklessly from neightbl_fill_info()
4) neightbl_fill_info() reads cpu stats that can be changed concurrently.
Fixes: c7fb64db001f ("[NETLINK]: Neighbour table configuration and statistics via rtnetlink")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20231019122104.1448310-1-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index f16ec0e8a0348..4a1d669b46f90 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -251,7 +251,8 @@ bool neigh_remove_one(struct neighbour *ndel, struct neigh_table *tbl)
static int neigh_forced_gc(struct neigh_table *tbl)
{
- int max_clean = atomic_read(&tbl->gc_entries) - tbl->gc_thresh2;
+ int max_clean = atomic_read(&tbl->gc_entries) -
+ READ_ONCE(tbl->gc_thresh2);
unsigned long tref = jiffies - 5 * HZ;
struct neighbour *n, *tmp;
int shrunk = 0;
@@ -280,7 +281,7 @@ static int neigh_forced_gc(struct neigh_table *tbl)
}
}
- tbl->last_flush = jiffies;
+ WRITE_ONCE(tbl->last_flush, jiffies);
write_unlock_bh(&tbl->lock);
@@ -464,17 +465,17 @@ static struct neighbour *neigh_alloc(struct neigh_table *tbl,
{
struct neighbour *n = NULL;
unsigned long now = jiffies;
- int entries;
+ int entries, gc_thresh3;
if (exempt_from_gc)
goto do_alloc;
entries = atomic_inc_return(&tbl->gc_entries) - 1;
- if (entries >= tbl->gc_thresh3 ||
- (entries >= tbl->gc_thresh2 &&
- time_after(now, tbl->last_flush + 5 * HZ))) {
- if (!neigh_forced_gc(tbl) &&
- entries >= tbl->gc_thresh3) {
+ gc_thresh3 = READ_ONCE(tbl->gc_thresh3);
+ if (entries >= gc_thresh3 ||
+ (entries >= READ_ONCE(tbl->gc_thresh2) &&
+ time_after(now, READ_ONCE(tbl->last_flush) + 5 * HZ))) {
+ if (!neigh_forced_gc(tbl) && entries >= gc_thresh3) {
net_info_ratelimited("%s: neighbor table overflow!\n",
tbl->id);
NEIGH_CACHE_STAT_INC(tbl, table_fulls);
@@ -955,13 +956,14 @@ static void neigh_periodic_work(struct work_struct *work)
if (time_after(jiffies, tbl->last_rand + 300 * HZ)) {
struct neigh_parms *p;
- tbl->last_rand = jiffies;
+
+ WRITE_ONCE(tbl->last_rand, jiffies);
list_for_each_entry(p, &tbl->parms_list, list)
p->reachable_time =
neigh_rand_reach_time(NEIGH_VAR(p, BASE_REACHABLE_TIME));
}
- if (atomic_read(&tbl->entries) < tbl->gc_thresh1)
+ if (atomic_read(&tbl->entries) < READ_ONCE(tbl->gc_thresh1))
goto out;
for (i = 0 ; i < (1 << nht->hash_shift); i++) {
@@ -2167,15 +2169,16 @@ static int neightbl_fill_info(struct sk_buff *skb, struct neigh_table *tbl,
ndtmsg->ndtm_pad2 = 0;
if (nla_put_string(skb, NDTA_NAME, tbl->id) ||
- nla_put_msecs(skb, NDTA_GC_INTERVAL, tbl->gc_interval, NDTA_PAD) ||
- nla_put_u32(skb, NDTA_THRESH1, tbl->gc_thresh1) ||
- nla_put_u32(skb, NDTA_THRESH2, tbl->gc_thresh2) ||
- nla_put_u32(skb, NDTA_THRESH3, tbl->gc_thresh3))
+ nla_put_msecs(skb, NDTA_GC_INTERVAL, READ_ONCE(tbl->gc_interval),
+ NDTA_PAD) ||
+ nla_put_u32(skb, NDTA_THRESH1, READ_ONCE(tbl->gc_thresh1)) ||
+ nla_put_u32(skb, NDTA_THRESH2, READ_ONCE(tbl->gc_thresh2)) ||
+ nla_put_u32(skb, NDTA_THRESH3, READ_ONCE(tbl->gc_thresh3)))
goto nla_put_failure;
{
unsigned long now = jiffies;
- long flush_delta = now - tbl->last_flush;
- long rand_delta = now - tbl->last_rand;
+ long flush_delta = now - READ_ONCE(tbl->last_flush);
+ long rand_delta = now - READ_ONCE(tbl->last_rand);
struct neigh_hash_table *nht;
struct ndt_config ndc = {
.ndtc_key_len = tbl->key_len,
@@ -2183,7 +2186,7 @@ static int neightbl_fill_info(struct sk_buff *skb, struct neigh_table *tbl,
.ndtc_entries = atomic_read(&tbl->entries),
.ndtc_last_flush = jiffies_to_msecs(flush_delta),
.ndtc_last_rand = jiffies_to_msecs(rand_delta),
- .ndtc_proxy_qlen = tbl->proxy_queue.qlen,
+ .ndtc_proxy_qlen = READ_ONCE(tbl->proxy_queue.qlen),
};
rcu_read_lock();
@@ -2206,17 +2209,17 @@ static int neightbl_fill_info(struct sk_buff *skb, struct neigh_table *tbl,
struct neigh_statistics *st;
st = per_cpu_ptr(tbl->stats, cpu);
- ndst.ndts_allocs += st->allocs;
- ndst.ndts_destroys += st->destroys;
- ndst.ndts_hash_grows += st->hash_grows;
- ndst.ndts_res_failed += st->res_failed;
- ndst.ndts_lookups += st->lookups;
- ndst.ndts_hits += st->hits;
- ndst.ndts_rcv_probes_mcast += st->rcv_probes_mcast;
- ndst.ndts_rcv_probes_ucast += st->rcv_probes_ucast;
- ndst.ndts_periodic_gc_runs += st->periodic_gc_runs;
- ndst.ndts_forced_gc_runs += st->forced_gc_runs;
- ndst.ndts_table_fulls += st->table_fulls;
+ ndst.ndts_allocs += READ_ONCE(st->allocs);
+ ndst.ndts_destroys += READ_ONCE(st->destroys);
+ ndst.ndts_hash_grows += READ_ONCE(st->hash_grows);
+ ndst.ndts_res_failed += READ_ONCE(st->res_failed);
+ ndst.ndts_lookups += READ_ONCE(st->lookups);
+ ndst.ndts_hits += READ_ONCE(st->hits);
+ ndst.ndts_rcv_probes_mcast += READ_ONCE(st->rcv_probes_mcast);
+ ndst.ndts_rcv_probes_ucast += READ_ONCE(st->rcv_probes_ucast);
+ ndst.ndts_periodic_gc_runs += READ_ONCE(st->periodic_gc_runs);
+ ndst.ndts_forced_gc_runs += READ_ONCE(st->forced_gc_runs);
+ ndst.ndts_table_fulls += READ_ONCE(st->table_fulls);
}
if (nla_put_64bit(skb, NDTA_STATS, sizeof(ndst), &ndst,
@@ -2445,16 +2448,16 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh,
goto errout_tbl_lock;
if (tb[NDTA_THRESH1])
- tbl->gc_thresh1 = nla_get_u32(tb[NDTA_THRESH1]);
+ WRITE_ONCE(tbl->gc_thresh1, nla_get_u32(tb[NDTA_THRESH1]));
if (tb[NDTA_THRESH2])
- tbl->gc_thresh2 = nla_get_u32(tb[NDTA_THRESH2]);
+ WRITE_ONCE(tbl->gc_thresh2, nla_get_u32(tb[NDTA_THRESH2]));
if (tb[NDTA_THRESH3])
- tbl->gc_thresh3 = nla_get_u32(tb[NDTA_THRESH3]);
+ WRITE_ONCE(tbl->gc_thresh3, nla_get_u32(tb[NDTA_THRESH3]));
if (tb[NDTA_GC_INTERVAL])
- tbl->gc_interval = nla_get_msecs(tb[NDTA_GC_INTERVAL]);
+ WRITE_ONCE(tbl->gc_interval, nla_get_msecs(tb[NDTA_GC_INTERVAL]));
err = 0;
