git: 208256579804 - main - O_PATH: disable kqfilter for fifos

[Konstantin Belousov]

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=2082565798041ceb9fb77137f00ea6b0ff50fe5e

commit 2082565798041ceb9fb77137f00ea6b0ff50fe5e
Author:     Konstantin Belousov <kib at FreeBSD.org>
AuthorDate: 2021-04-28 15:45:36 +0000
Commit:     Konstantin Belousov <kib at FreeBSD.org>
CommitDate: 2021-04-30 14:43:45 +0000

    O_PATH: disable kqfilter for fifos
    
    Filter on fifos is real filter for the object, and not a filesystem
    events filter like EVFILT_VNODE.
    
    Reported by:    markj using syzkaller
    Reviewed by:    markj
    Sponsored by:   The FreeBSD Foundation
    MFC after:      3 days
---
 sys/kern/vfs_vnops.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index f715c9828d04..832c717a33b7 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -427,7 +427,10 @@ vn_open_vnode(struct vnode *vp, int fmode, struct ucred *cred,
 			return (error);
 	}
 	if ((fmode & O_PATH) != 0) {
-		error = VOP_ACCESS(vp, VREAD, cred, td);
+		if (vp->v_type == VFIFO)
+			error = EPIPE;
+		else
+			error = VOP_ACCESS(vp, VREAD, cred, td);
 		if (error == 0)
 			fp->f_flag |= FKQALLOWED;
 		return (0);