Date: Wed, 5 Mar 1997 04:01:49 +0900 (JST) From: kato@eclogite.eps.nagoya-u.ac.jp To: FreeBSD-gnats-submit@freebsd.org Subject: kern/2875: vinvalbuf() clobbers b_vnbufs chain Message-ID: <199703041901.EAA01847@gneiss.eps.nagoya-u.ac.jp> Resent-Message-ID: <199703041910.LAA08444@freefall.freebsd.org>
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>Number: 2875
>Category: kern
>Synopsis: vinvalbuf() may clobber b_vnbufs chain.
>Confidential: no
>Severity: critical
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Tue Mar 4 11:10:01 PST 1997
>Last-Modified:
>Originator: KATO Takenori
>Organization:
Dept. Earth Planet. Sci, Nagoya Univ, Japan
>Release: FreeBSD 2.2-GAMMA i386
>Environment:
>Description:
The function vinvalbuf() in vfs_subr.c may clober b_vnbufs chain.
in vinvalbuf():
s = splbio();
for (;;) {
...
for (bp = blist; bp; bp = nbp) {
...
if (bp->b_flags & B_BUSY) {
...
splx(s); <--- (1)
...
break; <--- (2)
}
}
}
Because disk I/O interruption is unmasked at (1), b_vnbufs is operated
without splbio() after `break' at (2).
>How-To-Repeat:
>Fix:
*** vfs_subr.c.orig Wed Mar 5 03:03:56 1997
--- vfs_subr.c Wed Mar 5 03:44:00 1997
***************
*** 481,488 ****
panic("vinvalbuf: dirty bufs");
}
- s = splbio();
for (;;) {
if ((blist = vp->v_cleanblkhd.lh_first) && (flags & V_SAVEMETA))
while (blist && blist->b_lblkno < 0)
blist = blist->b_vnbufs.le_next;
--- 481,488 ----
panic("vinvalbuf: dirty bufs");
}
for (;;) {
+ s = splbio();
if ((blist = vp->v_cleanblkhd.lh_first) && (flags & V_SAVEMETA))
while (blist && blist->b_lblkno < 0)
blist = blist->b_vnbufs.le_next;
***************
*** 502,510 ****
error = tsleep((caddr_t) bp,
slpflag | (PRIBIO + 1), "vinvalbuf",
slptimeo);
! splx(s);
! if (error)
return (error);
break;
}
bremfree(bp);
--- 502,511 ----
error = tsleep((caddr_t) bp,
slpflag | (PRIBIO + 1), "vinvalbuf",
slptimeo);
! if (error) {
! splx(s);
return (error);
+ }
break;
}
bremfree(bp);
***************
*** 522,527 ****
--- 523,529 ----
bp->b_flags |= (B_INVAL|B_NOCACHE|B_RELBUF);
brelse(bp);
}
+ splx(s);
}
splx(s);
>Audit-Trail:
>Unformatted:
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