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

[Hannes Reinecke]

On 04/04/2017 08:56 PM, 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@xxxxxx>
> Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
> ---
>  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;
> 
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@xxxxxxx			               +49 911 74053 688
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