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ping: Fix potentail NULL deref for /proc/net/icmp.

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After commit dbca1596bb ("ping: convert to RCU lookups, get rid
of rwlock"), we use RCU for ping sockets, but we should use spinlock
for /proc/net/icmp to avoid a potential NULL deref mentioned in
the previous patch.

Let's go back to using spinlock there.

Note we can convert ping sockets to use hlist instead of hlist_nulls
because we do not use SLAB_TYPESAFE_BY_RCU for ping sockets.

Fixes: dbca1596bb ("ping: convert to RCU lookups, get rid of rwlock")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2023-04-03 12:49:59 -07:00 committed by Jakub Kicinski
parent 0a78cf7264
commit ab5fb73ffa
1 changed files with 4 additions and 4 deletions
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8
net/ipv4/ping.c
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@ -1089,13 +1089,13 @@ static struct sock *ping_get_idx(struct seq_file *seq, loff_t pos)
}
void *ping_seq_start(struct seq_file *seq, loff_t *pos, sa_family_t family)
__acquires(RCU)
__acquires(ping_table.lock)
{
struct ping_iter_state *state = seq->private;
state->bucket = 0;
state->family = family;
rcu_read_lock();
spin_lock(&ping_table.lock);
return *pos ? ping_get_idx(seq, *pos-1) : SEQ_START_TOKEN;
}
@ -1121,9 +1121,9 @@ void *ping_seq_next(struct seq_file *seq, void *v, loff_t *pos)
EXPORT_SYMBOL_GPL(ping_seq_next);
void ping_seq_stop(struct seq_file *seq, void *v)
__releases(RCU)
__releases(ping_table.lock)
{
rcu_read_unlock();
spin_unlock(&ping_table.lock);
}
EXPORT_SYMBOL_GPL(ping_seq_stop);