git: a9ef2c901a8b - stable/14 - socket: Don't assume m0 != NULL in sbappendcontrol_locked()

The branch stable/14 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=a9ef2c901a8b7101414a6bb778f991e9cb3b50c9

commit a9ef2c901a8b7101414a6bb778f991e9cb3b50c9
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2024-02-02 18:58:37 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2024-02-09 14:56:02 +0000

    socket: Don't assume m0 != NULL in sbappendcontrol_locked()
    
    Some callers (e.g., ktls_decrypt()) violate this assumption and thus
    could trigger a NULL pointer dereference in KMSAN kernels.
    
    Reported by:    glebius
    Fixes:          ec45f952a232 ("sockbuf: Add KMSAN checks to sbappend*()")
    MFC after:      1 week
    
    (cherry picked from commit 30f8cb812e27d8ab40a2c0669ac20a8ee45a7c56)
---
 sys/kern/uipc_sockbuf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sys/kern/uipc_sockbuf.c b/sys/kern/uipc_sockbuf.c
index e76f198f42dc..406fdca11b47 100644
--- a/sys/kern/uipc_sockbuf.c
+++ b/sys/kern/uipc_sockbuf.c
@@ -1328,7 +1328,8 @@ sbappendcontrol_locked(struct sockbuf *sb, struct mbuf *m0,
 {
 	struct mbuf *m, *mlast;
 
-	kmsan_check_mbuf(m0, "sbappend");
+	if (m0 != NULL)
+		kmsan_check_mbuf(m0, "sbappend");
 	kmsan_check_mbuf(control, "sbappend");
 
 	sbm_clrprotoflags(m0, flags);