Re: [PATCH 1/7] bio-integrity: Do not allocate integrity context for bio w/o data

[Christoph Hellwig]

Looks good,

Reviewed-by: Christoph Hellwig 

[PATCH 1/7] bio-integrity: Do not allocate integrity context for bio w/o data

[Dmitry Monakhov]

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:  [#1] SMP
Modules linked in: bcache
CPU: 0 PID: 4428 Comm: xfs_io Tainted: GW   
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: 880137786440 task.stack: c9ba8000
RIP: 0010:kfree_debugcheck+0x25/0x2a
RSP: 0018:c9babde0 EFLAGS: 00010082
RAX: 0034 RBX: ac1fa1d106742a5a RCX: 0007
RDX:  RSI:  RDI: 88013f3ccb40
RBP: c9babde8 R08:  R09: 
R10: fcb76420 R11: 725172ed R12: 0282
R13: 8150e766 R14: 88013a145e00 R15: 0001
FS:  7fb09384bf40() GS:88013f20() knlGS:
CS:  0010 DS:  ES:  CR0: 80050033
CR2: 7fd0172f9e40 CR3: 000137fa9000 CR4: 06f0
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

Signed-off-by: Dmitry Monakhov 
---
 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