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linux/drivers/virt
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Dan Williams cb051977e9 virt: sevguest: Fix passing a stack buffer as a scatterlist target 
[ Upstream commit db10cb9b57 ]

CONFIG_DEBUG_SG highlights that get_{report,ext_report,derived_key)()}
are passing stack buffers as the @req_buf argument to
handle_guest_request(), generating a Call Trace of the following form:

    WARNING: CPU: 0 PID: 1175 at include/linux/scatterlist.h:187 enc_dec_message+0x518/0x5b0 [sev_guest]
    [..]
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
    RIP: 0010:enc_dec_message+0x518/0x5b0 [sev_guest]
    Call Trace:
     <TASK>
    [..]
     handle_guest_request+0x135/0x520 [sev_guest]
     get_ext_report+0x1ec/0x3e0 [sev_guest]
     snp_guest_ioctl+0x157/0x200 [sev_guest]

Note that the above Call Trace was with the DEBUG_SG BUG_ON()s converted
to WARN_ON()s.

This is benign as long as there are no hardware crypto accelerators
loaded for the aead cipher, and no subsequent dma_map_sg() is performed
on the scatterlist. However, sev-guest can not assume the presence of
an aead accelerator nor can it assume that CONFIG_DEBUG_SG is disabled.

Resolve this bug by allocating virt_addr_valid() memory, similar to the
other buffers am @snp_dev instance carries, to marshal requests from
user buffers to kernel buffers.

Reported-by: Peter Gonda <pgonda@google.com>
Closes: http://lore.kernel.org/r/CAMkAt6r2VPPMZ__SQfJse8qWsUyYW3AgYbOUVM0S_Vtk=KvkxQ@mail.gmail.com
Fixes: fce96cf044 ("virt: Add SEV-SNP guest driver")
Cc: Borislav Petkov <bp@alien8.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Dionna Glaze <dionnaglaze@google.com>
Cc: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Tested-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-11-20 11:59:30 +01:00
..
acrn minmax: add in_range() macro 2023-08-24 16:20:18 -07:00
coco virt: sevguest: Fix passing a stack buffer as a scatterlist target 2023-11-20 11:59:30 +01:00
nitro_enclaves kunit: fix Kconfig for build-in tests USB4 and Nitro Enclaves 2022-09-01 13:00:48 -06:00
vboxguest virt: vbox: Remove unproper information 2022-09-09 10:19:18 +02:00
fsl_hypervisor.c virt: fsl: Use of_property_present() for testing DT property presence 2023-04-21 09:20:56 -05:00
Kconfig virt: Add TDX guest driver 2022-11-17 11:04:23 -08:00
Makefile virt: Add TDX guest driver 2022-11-17 11:04:23 -08:00
vmgenid.c virt: vmgenid: recognize new CID added by Hyper-V 2022-03-25 08:49:40 -06:00