Date: Fri, 8 Feb 2019 08:17:31 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r343898 - head/sys/fs/nullfs Message-ID: <201902080817.x188HVYE023885@repo.freebsd.org>
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Author: kib Date: Fri Feb 8 08:17:31 2019 New Revision: 343898 URL: https://svnweb.freebsd.org/changeset/base/343898 Log: Before using VTONULL(), check that the covered vnode belongs to nullfs. Reported and tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Modified: head/sys/fs/nullfs/null_vfsops.c Modified: head/sys/fs/nullfs/null_vfsops.c ============================================================================== --- head/sys/fs/nullfs/null_vfsops.c Fri Feb 8 08:15:29 2019 (r343897) +++ head/sys/fs/nullfs/null_vfsops.c Fri Feb 8 08:17:31 2019 (r343898) @@ -145,10 +145,13 @@ nullfs_mount(struct mount *mp) /* * Check multi null mount to avoid `lock against myself' panic. */ - if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { - NULLFSDEBUG("nullfs_mount: multi null mount?\n"); - vput(lowerrootvp); - return (EDEADLK); + if (mp->mnt_vnodecovered->v_op == &null_vnodeops) { + nn = VTONULL(mp->mnt_vnodecovered); + if (nn == NULL || lowerrootvp == nn->null_lowervp) { + NULLFSDEBUG("nullfs_mount: multi null mount?\n"); + vput(lowerrootvp); + return (EDEADLK); + } } xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
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