Date: Tue, 26 Feb 2002 10:37:15 +0900
From: Jun Kuriyama <kuriyama@imgsrc.co.jp>
To: Current <FreeBSD-current@FreeBSD.org>
Subject: struct {bio,buf} pointer for bioqdisksort()
Message-ID: <7mg03p9g6s.wl@waterblue.imgsrc.co.jp>
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In arstrategy() at dev/ata/ata-raid.c, memory is allocated with size
of "struct ar_buf" and passed as "struct bio*".
> buf1 = malloc(sizeof(struct ar_buf), M_AR, M_NOWAIT | M_ZERO);
...
> buf1->bp.bio_dev->AD_STRATEGY((struct bio *)buf1);
This works fine because "struct ar_buf" contains "struct bio" as first
member.
> struct ar_buf {
> struct bio bp;
...
This pointer is passed to bioqdisksort() as "struct bio*".
In bioqdisksort() at kern/subr_disklabel.c, "struct bio *bp" is
converted into "struct buf*" with BIOTOBUF() macro.
> void
> bioqdisksort(bioq, bp)
> struct bio_queue_head *bioq;
> struct bio *bp;
> {
...
> if (td && td->td_ksegrp->kg_nice > 0) {
> TAILQ_FOREACH(bn, &bioq->queue, bio_queue)
> if (BIOTOBUF(bp)->b_vp != BIOTOBUF(bn)->b_vp)
> break;
On my environment, this causes panic because "*bp" does not have
enough allocated region.
(kgdb) p sizeof(struct bio)
$1 = 80
(kgdb) p sizeof(struct ar_buf)
$2 = 96
(kgdb) p sizeof(struct buf)
$3 = 364
I'm not familiar with this area, but I think
(1) arstrategy() should allocate enough size to cover "struct buf" for
"struct ar_buf",
(2) bioqdisksort() should not suppose "struct bio *bp" can be
converted into "struct buf*", or
(3) Call chain such as arstrategy() -> adstrategy() -> bioqdisksort()
is wrong.
Can someone explain what I should do next about this?
--
Jun Kuriyama <kuriyama@imgsrc.co.jp> // IMG SRC, Inc.
<kuriyama@FreeBSD.org> // FreeBSD Project
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