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Fix use-after-free in case of L2ARC prefetch failure.

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In case L2ARC read failed, l2arc_read_done() creates _different_ ZIO
to read data from the original storage device.  Unfortunately pointer
to the failed ZIO remains in hdr->b_l1hdr.b_acb->acb_zio_head, and if
some other read try to bump the ZIO priority, it will crash.

The problem is reproducible by corrupting L2ARC content and reading
some data with prefetch if l2arc_noprefetch tunable is changed to 0.
With the default setting the issue is probably not reproducible now.

MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
This commit is contained in:
Alexander Motin 2019-11-28 18:28:35 +00:00
parent 6903d37518
commit 5008399c14
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=355182
1 changed files with 9 additions and 4 deletions
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13
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
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@ -7886,7 +7886,6 @@ l2arc_read_done(zio_t *zio)
zio->io_private = hdr;
arc_read_done(zio);
} else {
mutex_exit(hash_lock);
/*
* Buffer didn't survive caching. Increment stats and
* reissue to the original storage device.
@ -7909,11 +7908,17 @@ l2arc_read_done(zio_t *zio)
ASSERT(!pio || pio->io_child_type == ZIO_CHILD_LOGICAL);
zio_nowait(zio_read(pio, zio->io_spa, zio->io_bp,
zio = zio_read(pio, zio->io_spa, zio->io_bp,
hdr->b_l1hdr.b_pabd, zio->io_size, arc_read_done,
hdr, zio->io_priority, cb->l2rcb_flags,
&cb->l2rcb_zb));
}
&cb->l2rcb_zb);
for (struct arc_callback *acb = hdr->b_l1hdr.b_acb;
acb != NULL; acb = acb->acb_next)
acb->acb_zio_head = zio;
mutex_exit(hash_lock);
zio_nowait(zio);
} else
mutex_exit(hash_lock);
}
kmem_free(cb, sizeof (l2arc_read_callback_t));