Date: Thu, 3 Apr 1997 07:30:04 -0800 (PST) From: Tor Egge <Tor.Egge@idi.ntnu.no> To: freebsd-bugs Subject: Re: kern/3184: vnodes are used after they are freed. Message-ID: <199704031530.HAA27623@freefall.freebsd.org>
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The following reply was made to PR kern/3184; it has been noted by GNATS.
From: Tor Egge <Tor.Egge@idi.ntnu.no>
To: FreeBSD-gnats-submit@freebsd.org
Cc: Subject: Re: kern/3184: vnodes are used after they are freed.
Date: Thu, 03 Apr 1997 17:21:56 +0200
I wrote:
> >Fix:
>
> Insert the vnode onto the freelist AFTER having called VOP_INACTIVE.
>
> Untested (but compileable) diff:
A magic number was needed to avoid instant crashes.
Index: vfs_subr.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/vfs_subr.c,v
retrieving revision 1.81
diff -c -r1.81 vfs_subr.c
*** vfs_subr.c 1997/04/01 13:05:34 1.81
--- vfs_subr.c 1997/04/03 16:31:00
***************
*** 1049,1066 ****
#endif
panic("vputrele: negative ref cnt");
}
! simple_lock(&vnode_free_list_slock);
! if (vp->v_flag & VAGE) {
! vp->v_flag &= ~VAGE;
! vp->v_usage = 0;
! if(vp->v_tag != VT_TFS)
! TAILQ_INSERT_HEAD(&vnode_free_list, vp, v_freelist);
! } else {
! if(vp->v_tag != VT_TFS)
! TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
! }
! freevnodes++;
! simple_unlock(&vnode_free_list_slock);
/*
* If we are doing a vput, the node is already locked, and we must
--- 1049,1056 ----
#endif
panic("vputrele: negative ref cnt");
}
! /* see comment on why 0xdeadb is set at end of vgone (below) */
! vp->v_freelist.tqe_prev = (struct vnode **) 0xdeadb;
/*
* If we are doing a vput, the node is already locked, and we must
***************
*** 1073,1078 ****
--- 1063,1081 ----
} else if (vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK, p) == 0) {
VOP_INACTIVE(vp, p);
}
+
+ simple_lock(&vnode_free_list_slock);
+ if (vp->v_flag & VAGE) {
+ vp->v_flag &= ~VAGE;
+ vp->v_usage = 0;
+ if(vp->v_tag != VT_TFS)
+ TAILQ_INSERT_HEAD(&vnode_free_list, vp, v_freelist);
+ } else {
+ if(vp->v_tag != VT_TFS)
+ TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
+ }
+ freevnodes++;
+ simple_unlock(&vnode_free_list_slock);
}
/*
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