[RFC RFT PATCH 4/4] uio_hv_generic: Don't free decrypted memory
From: Rick Edgecombe <rick.p.edgecombe@intel.com>
Date: 2024-02-22 02:10:45
Also in:
linux-coco, linux-hyperv, lkml
Subsystem:
hyper-v/azure core and drivers, the rest, userspace i/o (uio) · Maintainers:
"K. Y. Srinivasan", Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Linus Torvalds, Greg Kroah-Hartman
On TDX it is possible for the untrusted host to cause set_memory_encrypted() or set_memory_decrypted() to fail such that an error is returned and the resulting memory is shared. Callers need to take care to handle these errors to avoid returning decrypted (shared) memory to the page allocator, which could lead to functional or security issues. uio_hv_generic could free decrypted/shared pages if set_memory_decrypted() fails. Check the decrypted field in the gpadl before freeing in order to not leak the memory. Only compile tested. Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Wei Liu <wei.liu@kernel.org> Cc: Dexuan Cui <decui@microsoft.com> Cc: linux-hyperv@vger.kernel.org Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> --- drivers/uio/uio_hv_generic.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/uio/uio_hv_generic.c b/drivers/uio/uio_hv_generic.c
index 20d9762331bd..6be3462b109f 100644
--- a/drivers/uio/uio_hv_generic.c
+++ b/drivers/uio/uio_hv_generic.c@@ -181,12 +181,14 @@ hv_uio_cleanup(struct hv_device *dev, struct hv_uio_private_data *pdata) { if (pdata->send_gpadl.gpadl_handle) { vmbus_teardown_gpadl(dev->channel, &pdata->send_gpadl); - vfree(pdata->send_buf); + if (!pdata->send_gpadl.decrypted) + vfree(pdata->send_buf); } if (pdata->recv_gpadl.gpadl_handle) { vmbus_teardown_gpadl(dev->channel, &pdata->recv_gpadl); - vfree(pdata->recv_buf); + if (!pdata->recv_gpadl.decrypted) + vfree(pdata->recv_buf); } }
@@ -295,7 +297,8 @@ hv_uio_probe(struct hv_device *dev, ret = vmbus_establish_gpadl(channel, pdata->recv_buf, RECV_BUFFER_SIZE, &pdata->recv_gpadl); if (ret) { - vfree(pdata->recv_buf); + if (!pdata->recv_gpadl.decrypted) + vfree(pdata->recv_buf); goto fail_close; }
@@ -317,7 +320,8 @@ hv_uio_probe(struct hv_device *dev, ret = vmbus_establish_gpadl(channel, pdata->send_buf, SEND_BUFFER_SIZE, &pdata->send_gpadl); if (ret) { - vfree(pdata->send_buf); + if (!pdata->send_gpadl.decrypted) + vfree(pdata->send_buf); goto fail_close; }
--
2.34.1