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authorLong Li <longli@microsoft.com>2018-01-10 13:21:29 -0700
committerSasha Levin <alexander.levin@microsoft.com>2018-01-21 09:59:00 -0500
commit623dfab42becf5c56c9a31b7eaf90cb6eb86459f (patch)
treed1e75ba7235b5978ab3f4a60584dc71d7f1ec4e6
parentfeedfe2129e348e075b72a5e3e1c7c52d0c769e4 (diff)
storvsc: do not assume SG list is continuous when doing bounce buffers
The original patch was made for stable 4.1 and was Acked on 08/22/2017, but for some reason it never made it to the stable tree. Change from v1: Changed comment that this patch is for linux-stable 4.1 and all prior stable kernels. storvsc checks the SG list for gaps before passing them to Hyper-v device. If there are gaps, data is copied to a bounce buffer and a continuous data buffer is passed to Hyper-V. The check on gaps assumes SG list is continuous, and not chained. This is not always true. Failing the check may result in incorrect I/O data passed to the Hyper-v device. This code path is not used post Linux 4.1. [LL: Backport for 4.1] Signed-off-by: Long Li <longli@microsoft.com> Acked-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
-rw-r--r--drivers/scsi/storvsc_drv.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index e4b103d5d289..98b56a7069d3 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -582,17 +582,18 @@ static int do_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count)
for (i = 0; i < sg_count; i++) {
if (i == 0) {
/* make sure 1st one does not have hole */
- if (sgl[i].offset + sgl[i].length != PAGE_SIZE)
+ if (sgl->offset + sgl->length != PAGE_SIZE)
return i;
} else if (i == sg_count - 1) {
/* make sure last one does not have hole */
- if (sgl[i].offset != 0)
+ if (sgl->offset != 0)
return i;
} else {
/* make sure no hole in the middle */
- if (sgl[i].length != PAGE_SIZE || sgl[i].offset != 0)
+ if (sgl->length != PAGE_SIZE || sgl->offset != 0)
return i;
}
+ sgl = sg_next(sgl);
}
return -1;
}