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authorMichael Kelley <mikelley@microsoft.com>2022-12-04 22:52:44 +0300
committerMartin K. Petersen <martin.petersen@oracle.com>2022-12-14 05:54:44 +0300
commit67ff3d0a49f3d445c3922e30a54e03c161da561e (patch)
tree445c362121cd8ec2187901f566a3186a0a4f8b17 /drivers/scsi
parenta3be19b91ea7121d388084e8c07f5b1b982eb40c (diff)
downloadlinux-67ff3d0a49f3d445c3922e30a54e03c161da561e.tar.xz
scsi: storvsc: Fix swiotlb bounce buffer leak in confidential VM
storvsc_queuecommand() maps the scatter/gather list using scsi_dma_map(), which in a confidential VM allocates swiotlb bounce buffers. If the I/O submission fails in storvsc_do_io(), the I/O is typically retried by higher level code, but the bounce buffer memory is never freed. The mostly like cause of I/O submission failure is a full VMBus channel ring buffer, which is not uncommon under high I/O loads. Eventually enough bounce buffer memory leaks that the confidential VM can't do any I/O. The same problem can arise in a non-confidential VM with kernel boot parameter swiotlb=force. Fix this by doing scsi_dma_unmap() in the case of an I/O submission error, which frees the bounce buffer memory. Fixes: 743b237c3a7b ("scsi: storvsc: Add Isolation VM support for storvsc driver") Signed-off-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1670183564-76254-1-git-send-email-mikelley@microsoft.com Tested-by: Dexuan Cui <decui@microsoft.com> Reviewed-by: Dexuan Cui <decui@microsoft.com> Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/storvsc_drv.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index a84194d82347..0252ee2dd844 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1824,6 +1824,9 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
ret = storvsc_do_io(dev, cmd_request, get_cpu());
put_cpu();
+ if (ret)
+ scsi_dma_unmap(scmnd);
+
if (ret == -EAGAIN) {
/* no more space */
ret = SCSI_MLQUEUE_DEVICE_BUSY;