git: 8c5796ba8e32 - stable/13 - sctp: improve locking

The branch stable/13 has been updated by tuexen:

URL: https://cgit.FreeBSD.org/src/commit/?id=8c5796ba8e329c9e202e0e914e8e98fed4cd2248

commit 8c5796ba8e329c9e202e0e914e8e98fed4cd2248
Author:     Michael Tuexen <tuexen@FreeBSD.org>
AuthorDate: 2022-04-27 14:07:31 +0000
Commit:     Michael Tuexen <tuexen@FreeBSD.org>
CommitDate: 2023-02-01 22:46:14 +0000

    sctp: improve locking
    
    While there, do some cleanup.
    
    Reported by:    syzbot+f475e054c454310bc26d@syzkaller.appspotmail.com
    
    (cherry picked from commit 490a0f77de77321859eeeecc807f9cc7bb41dbcc)
---
 sys/netinet/sctputil.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/sys/netinet/sctputil.c b/sys/netinet/sctputil.c
index 9405814d3d13..dad937f15172 100644
--- a/sys/netinet/sctputil.c
+++ b/sys/netinet/sctputil.c
@@ -4870,8 +4870,9 @@ sctp_add_to_readq(struct sctp_inpcb *inp,
 #endif
 		return;
 	}
-	if (inp_read_lock_held == 0)
+	if (inp_read_lock_held == SCTP_READ_LOCK_NOT_HELD) {
 		SCTP_INP_READ_LOCK(inp);
+	}
 	if (inp->sctp_flags & SCTP_PCB_FLAGS_SOCKET_CANT_READ) {
 		if (!control->on_strm_q) {
 			sctp_free_remote_addr(control->whoFrom);
@@ -4881,8 +4882,9 @@ sctp_add_to_readq(struct sctp_inpcb *inp,
 			}
 			sctp_free_a_readq(stcb, control);
 		}
-		if (inp_read_lock_held == 0)
+		if (inp_read_lock_held == SCTP_READ_LOCK_NOT_HELD) {
 			SCTP_INP_READ_UNLOCK(inp);
+		}
 		return;
 	}
 	if (!(control->spec_flags & M_NOTIFICATION)) {
@@ -4894,7 +4896,7 @@ sctp_add_to_readq(struct sctp_inpcb *inp,
 	m = control->data;
 	control->held_length = 0;
 	control->length = 0;
-	while (m) {
+	while (m != NULL) {
 		if (SCTP_BUF_LEN(m) == 0) {
 			/* Skip mbufs with NO length */
 			if (prev == NULL) {
@@ -4938,11 +4940,12 @@ sctp_add_to_readq(struct sctp_inpcb *inp,
 	}
 	TAILQ_INSERT_TAIL(&inp->read_queue, control, next);
 	control->on_read_q = 1;
-	if (inp_read_lock_held == 0)
-		SCTP_INP_READ_UNLOCK(inp);
-	if (inp && inp->sctp_socket) {
+	if ((inp != NULL) && (inp->sctp_socket != NULL)) {
 		sctp_wakeup_the_read_socket(inp, stcb, so_locked);
 	}
+	if (inp_read_lock_held == SCTP_READ_LOCK_NOT_HELD) {
+		SCTP_INP_READ_UNLOCK(inp);
+	}
 }
 
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