Re: [PATCH 1/9] bio-integrity: Do not allocate integrity context for bio w/o data

[Christoph Hellwig <hch@infradead.org>]

On Thu, May 11, 2017 at 12:30:32AM -0700, Christoph Hellwig wrote:
> Jens, can you pick this up for 4.12?

ping?

> On Wed, May 10, 2017 at 07:20:44PM +0400, Dmitry Monakhov wrote:
> > If bio has no data, such as ones from blkdev_issue_flush(),
> > then we have nothing to protect.
> > 
> > This patch prevent bugon like follows:
> > 
> > kfree_debugcheck: out of range ptr ac1fa1d106742a5ah
> > kernel BUG at mm/slab.c:2773!
> > invalid opcode: 0000 [#1] SMP
> > Modules linked in: bcache
> > CPU: 0 PID: 4428 Comm: xfs_io Tainted: G        W       4.11.0-rc4-ext4-00041-g2ef0043-dirty #43
> > Hardware name: Virtuozzo KVM, BIOS seabios-1.7.5-11.vz7.4 04/01/2014
> > task: ffff880137786440 task.stack: ffffc90000ba8000
> > RIP: 0010:kfree_debugcheck+0x25/0x2a
> > RSP: 0018:ffffc90000babde0 EFLAGS: 00010082
> > RAX: 0000000000000034 RBX: ac1fa1d106742a5a RCX: 0000000000000007
> > RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88013f3ccb40
> > RBP: ffffc90000babde8 R08: 0000000000000000 R09: 0000000000000000
> > R10: 00000000fcb76420 R11: 00000000725172ed R12: 0000000000000282
> > R13: ffffffff8150e766 R14: ffff88013a145e00 R15: 0000000000000001
> > FS:  00007fb09384bf40(0000) GS:ffff88013f200000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007fd0172f9e40 CR3: 0000000137fa9000 CR4: 00000000000006f0
> > Call Trace:
> >  kfree+0xc8/0x1b3
> >  bio_integrity_free+0xc3/0x16b
> >  bio_free+0x25/0x66
> >  bio_put+0x14/0x26
> >  blkdev_issue_flush+0x7a/0x85
> >  blkdev_fsync+0x35/0x42
> >  vfs_fsync_range+0x8e/0x9f
> >  vfs_fsync+0x1c/0x1e
> >  do_fsync+0x31/0x4a
> >  SyS_fsync+0x10/0x14
> >  entry_SYSCALL_64_fastpath+0x1f/0xc2
> > 
> > Reviewed-by: Christoph Hellwig <hch@lst.de>
> > Reviewed-by: Hannes Reinecke <hare@suse.com>
> > Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
> > Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
> > ---
> >  block/bio-integrity.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/block/bio-integrity.c b/block/bio-integrity.c
> > index 5384713..b5009a8 100644
> > --- a/block/bio-integrity.c
> > +++ b/block/bio-integrity.c
> > @@ -175,6 +175,9 @@ bool bio_integrity_enabled(struct bio *bio)
> >  	if (bio_op(bio) != REQ_OP_READ && bio_op(bio) != REQ_OP_WRITE)
> >  		return false;
> >  
> > +	if (!bio_sectors(bio))
> > +		return false;
> > +
> >  	/* Already protected? */
> >  	if (bio_integrity(bio))
> >  		return false;
> > -- 
> > 2.9.3
> > 
> ---end quoted text---
---end quoted text---