diff mbox series

[PATCHv2,2/2] phonet/pep: fix racy skb_queue_empty() use

Message ID 20240218081214.4806-2-remi@remlab.net (mailing list archive)
State Accepted
Commit 7d2a894d7f487dcb894df023e9d3014cf5b93fe5
Delegated to: Netdev Maintainers
Headers show
Series [PATCHv2,1/2] phonet: take correct lock to peek at the RX queue | expand

Checks

Context Check Description
netdev/series_format warning Single patches do not need cover letters; Target tree name not specified in the subject
netdev/tree_selection success Guessed tree name to be net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 940 this patch: 940
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 5 of 6 maintainers
netdev/build_clang success Errors and warnings before: 957 this patch: 957
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 957 this patch: 957
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 53 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-02-22--00-00 (tests: 1455)

Commit Message

Rémi Denis-Courmont Feb. 18, 2024, 8:12 a.m. UTC 
From: Rémi Denis-Courmont <courmisch@gmail.com>

The receive queues are protected by their respective spin-lock, not
the socket lock. This could lead to skb_peek() unexpectedly
returning NULL or a pointer to an already dequeued socket buffer.

Fixes: 9641458d3ec4 ("Phonet: Pipe End Point for Phonet Pipes protocol")
Signed-off-by: Rémi Denis-Courmont <courmisch@gmail.com>
---
 net/phonet/pep.c | 41 ++++++++++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 9 deletions(-)
diff mbox series

Patch

diff --git a/net/phonet/pep.c b/net/phonet/pep.c
index faba31f2eff2..3dd5f52bc1b5 100644
--- a/net/phonet/pep.c
+++ b/net/phonet/pep.c
@@ -917,6 +917,37 @@  static int pep_sock_enable(struct sock *sk, struct sockaddr *addr, int len)
 	return 0;
 }
 
+static unsigned int pep_first_packet_length(struct sock *sk)
+{
+	struct pep_sock *pn = pep_sk(sk);
+	struct sk_buff_head *q;
+	struct sk_buff *skb;
+	unsigned int len = 0;
+	bool found = false;
+
+	if (sock_flag(sk, SOCK_URGINLINE)) {
+		q = &pn->ctrlreq_queue;
+		spin_lock_bh(&q->lock);
+		skb = skb_peek(q);
+		if (skb) {
+			len = skb->len;
+			found = true;
+		}
+		spin_unlock_bh(&q->lock);
+	}
+
+	if (likely(!found)) {
+		q = &sk->sk_receive_queue;
+		spin_lock_bh(&q->lock);
+		skb = skb_peek(q);
+		if (skb)
+			len = skb->len;
+		spin_unlock_bh(&q->lock);
+	}
+
+	return len;
+}
+
 static int pep_ioctl(struct sock *sk, int cmd, int *karg)
 {
 	struct pep_sock *pn = pep_sk(sk);
@@ -929,15 +960,7 @@  static int pep_ioctl(struct sock *sk, int cmd, int *karg)
 			break;
 		}
 
-		lock_sock(sk);
-		if (sock_flag(sk, SOCK_URGINLINE) &&
-		    !skb_queue_empty(&pn->ctrlreq_queue))
-			*karg = skb_peek(&pn->ctrlreq_queue)->len;
-		else if (!skb_queue_empty(&sk->sk_receive_queue))
-			*karg = skb_peek(&sk->sk_receive_queue)->len;
-		else
-			*karg = 0;
-		release_sock(sk);
+		*karg = pep_first_packet_length(sk);
 		ret = 0;
 		break;