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[34.83.123.78]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39e6cb3284asm6236175a91.14.2026.09.19.15.17.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Sep 2026 15:17:36 -0700 (PDT) From: Hui Peng To: kuniyu@google.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] af_unix: fix u->inq_len accounting in manage_oob() and unix_stream_read_skb() Date: Sat, 19 Sep 2026 22:17:35 +0000 Message-ID: <20260919221735.3708237-1-benquike@gmail.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When an old OOB skb is replaced and discarded in manage_oob(), or when a fully consumed OOB skb is skipped in unix_stream_read_skb(), the discarded byte count is not subtracted from u->inq_len (or is subtracted inconsistently), causing SIOCINQ / FIONREAD to report stale positive byte counts on an empty AF_UNIX stream socket. Properly account u->inq_len when dropping or skipping consumed OOB skbs. Fixes: 314001f0bf92 ("af_unix: Add OOB support") Assisted-by: LLM Signed-off-by: Hui Peng --- diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 42cffeafc8c1..1770af3c2684 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2849,6 +2849,7 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sk_buff **last, WRITE_ONCE(u->oob_skb, NULL); if (!sock_flag(sk, SOCK_URGINLINE)) { + WRITE_ONCE(u->inq_len, u->inq_len - 1); __skb_unlink(skb, &sk->sk_receive_queue); unread_skb = skb; skb = skb_peek(&sk->sk_receive_queue); @@ -2884,6 +2885,7 @@ static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor) return err; mutex_lock(&u->iolock); +again: spin_lock(&queue->lock); skb = __skb_dequeue(queue); @@ -2893,6 +2895,12 @@ static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor) return -EAGAIN; } + if (!unix_skb_len(skb)) { + spin_unlock(&queue->lock); + consume_skb(skb); + goto again; + } + WRITE_ONCE(u->inq_len, u->inq_len - unix_skb_len(skb)); #if IS_ENABLED(CONFIG_AF_UNIX_OOB) @@ -2908,6 +2916,11 @@ static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor) spin_unlock(&queue->lock); + if (UNIXCB(skb).consumed) { + skb_pull(skb, UNIXCB(skb).consumed); + UNIXCB(skb).consumed = 0; + } + unix_orphan_scm(sk, skb); mutex_unlock(&u->iolock);