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| author | Eric Dumazet <edumazet@google.com> | 2022-01-13 01:22:29 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-01-27 09:19:54 +0100 |
| commit | 577d3c5291dcb8b760869f097f90684e84745175 (patch) | |
| tree | d3313ccfde19063eba188ef603a0a3de501d6f3a | |
| parent | 967ec4b059180679c392dc4a384df11214cb950e (diff) | |
| download | linux-stable-577d3c5291dcb8b760869f097f90684e84745175.tar.gz linux-stable-577d3c5291dcb8b760869f097f90684e84745175.tar.bz2 linux-stable-577d3c5291dcb8b760869f097f90684e84745175.zip | |
inet: frags: annotate races around fqdir->dead and fqdir->high_thresh
commit 91341fa0003befd097e190ec2a4bf63ad957c49a upstream.
Both fields can be read/written without synchronization,
add proper accessors and documentation.
Fixes: d5dd88794a13 ("inet: fix various use-after-free in defrags units")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/net/inet_frag.h | 11 | ||||
| -rw-r--r-- | include/net/ipv6_frag.h | 3 | ||||
| -rw-r--r-- | net/ipv4/inet_fragment.c | 8 | ||||
| -rw-r--r-- | net/ipv4/ip_fragment.c | 3 |
4 files changed, 18 insertions, 7 deletions
diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h index bac79e817776..4cbd413e71a3 100644 --- a/include/net/inet_frag.h +++ b/include/net/inet_frag.h @@ -116,8 +116,15 @@ int fqdir_init(struct fqdir **fqdirp, struct inet_frags *f, struct net *net); static inline void fqdir_pre_exit(struct fqdir *fqdir) { - fqdir->high_thresh = 0; /* prevent creation of new frags */ - fqdir->dead = true; + /* Prevent creation of new frags. + * Pairs with READ_ONCE() in inet_frag_find(). + */ + WRITE_ONCE(fqdir->high_thresh, 0); + + /* Pairs with READ_ONCE() in inet_frag_kill(), ip_expire() + * and ip6frag_expire_frag_queue(). + */ + WRITE_ONCE(fqdir->dead, true); } void fqdir_exit(struct fqdir *fqdir); diff --git a/include/net/ipv6_frag.h b/include/net/ipv6_frag.h index a21e8b1381a1..e47a946bb77c 100644 --- a/include/net/ipv6_frag.h +++ b/include/net/ipv6_frag.h @@ -67,7 +67,8 @@ ip6frag_expire_frag_queue(struct net *net, struct frag_queue *fq) struct sk_buff *head; rcu_read_lock(); - if (fq->q.fqdir->dead) + /* Paired with the WRITE_ONCE() in fqdir_pre_exit(). */ + if (READ_ONCE(fq->q.fqdir->dead)) goto out_rcu_unlock; spin_lock(&fq->q.lock); diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c index 10d31733297d..e0e8a65d561e 100644 --- a/net/ipv4/inet_fragment.c +++ b/net/ipv4/inet_fragment.c @@ -204,9 +204,9 @@ void inet_frag_kill(struct inet_frag_queue *fq) /* The RCU read lock provides a memory barrier * guaranteeing that if fqdir->dead is false then * the hash table destruction will not start until - * after we unlock. Paired with inet_frags_exit_net(). + * after we unlock. Paired with fqdir_pre_exit(). */ - if (!fqdir->dead) { + if (!READ_ONCE(fqdir->dead)) { rhashtable_remove_fast(&fqdir->rhashtable, &fq->node, fqdir->f->rhash_params); refcount_dec(&fq->refcnt); @@ -321,9 +321,11 @@ static struct inet_frag_queue *inet_frag_create(struct fqdir *fqdir, /* TODO : call from rcu_read_lock() and no longer use refcount_inc_not_zero() */ struct inet_frag_queue *inet_frag_find(struct fqdir *fqdir, void *key) { + /* This pairs with WRITE_ONCE() in fqdir_pre_exit(). */ + long high_thresh = READ_ONCE(fqdir->high_thresh); struct inet_frag_queue *fq = NULL, *prev; - if (!fqdir->high_thresh || frag_mem_limit(fqdir) > fqdir->high_thresh) + if (!high_thresh || frag_mem_limit(fqdir) > high_thresh) return NULL; rcu_read_lock(); diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c index cfeb8890f94e..fad803d2d711 100644 --- a/net/ipv4/ip_fragment.c +++ b/net/ipv4/ip_fragment.c @@ -144,7 +144,8 @@ static void ip_expire(struct timer_list *t) rcu_read_lock(); - if (qp->q.fqdir->dead) + /* Paired with WRITE_ONCE() in fqdir_pre_exit(). */ + if (READ_ONCE(qp->q.fqdir->dead)) goto out_rcu_unlock; spin_lock(&qp->q.lock); |