From: Sean Christopherson seanjc@google.com
[ Upstream commit 74c1f1366eb7714b8b211554f6c5cee315ff3fbc ]
Explicitly reject using pointers that are not virt_to_phys() friendly as the source for SEV commands that are sent to the PSP. The PSP works with physical addresses, and __pa()/virt_to_phys() will not return the correct address in these cases, e.g. for a vmalloc'd pointer. At best, the bogus address will cause the command to fail, and at worst lead to system instability.
While it's unlikely that callers will deliberately use a bad pointer for SEV buffers, a caller can easily use a vmalloc'd pointer unknowingly when running with CONFIG_VMAP_STACK=y as it's not obvious that putting the command buffers on the stack would be bad. The command buffers are relative small and easily fit on the stack, and the APIs to do not document that the incoming pointer must be a physically contiguous, __pa() friendly pointer.
Cc: Brijesh Singh brijesh.singh@amd.com Cc: Borislav Petkov bp@suse.de Cc: Tom Lendacky thomas.lendacky@amd.com Cc: Christophe Leroy christophe.leroy@csgroup.eu Fixes: 200664d5237f ("crypto: ccp: Add Secure Encrypted Virtualization (SEV) command support") Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20210406224952.4177376-3-seanjc@google.com Reviewed-by: Brijesh Singh brijesh.singh@amd.com Acked-by: Tom Lendacky thomas.lendacky@amd.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/crypto/ccp/sev-dev.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 476113e12489..5b82ba7acc7c 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -149,6 +149,9 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
sev = psp->sev_data;
+ if (data && WARN_ON_ONCE(!virt_addr_valid(data))) + return -EINVAL; + /* Get the physical address of the command buffer */ phys_lsb = data ? lower_32_bits(__psp_pa(data)) : 0; phys_msb = data ? upper_32_bits(__psp_pa(data)) : 0;