RE: [RFC RFT PATCH 3/4] hv_nstvsc: Don't free decrypted memory
From: Michael Kelley <hidden>
Date: 2024-03-01 19:01:11
Also in:
linux-coco, linux-hyperv, lkml
From: Rick Edgecombe <rick.p.edgecombe@intel.com> Sent: Wednesday, February 21, 2024 6:10 PM
"Subject:" prefix should be hv_netvsc:
On TDX it is possible for the untrusted host to cause
Same comment about TDX vs. CoCo VM.
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. hv_nstvsc could free decrypted/shared pages if set_memory_decrypted()
s/hv_nstvsc/hv_netvsc/
quoted hunk ↗ jump to hunk
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/net/hyperv/netvsc.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c index a6fcbda64ecc..2b6ec979a62f 100644 --- a/drivers/net/hyperv/netvsc.c +++ b/drivers/net/hyperv/netvsc.c@@ -154,8 +154,11 @@ static void free_netvsc_device(struct rcu_head*head) int i; kfree(nvdev->extension); - vfree(nvdev->recv_buf); - vfree(nvdev->send_buf); + + if (!nvdev->recv_buf_gpadl_handle.decrypted) + vfree(nvdev->recv_buf); + if (!nvdev->send_buf_gpadl_handle.decrypted) + vfree(nvdev->send_buf); bitmap_free(nvdev->send_section_map); for (i = 0; i < VRSS_CHANNEL_MAX; i++) { -- 2.34.1