From: Long Li longli@microsoft.com
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.
Signed-off-by: Long Li longli@microsoft.com Acked-by: Martin K. Petersen martin.petersen@oracle.com
--- drivers/scsi/storvsc_drv.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index 6c52d14..14dc5c6 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -584,17 +584,18 @@ 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; }