From: Sean Christopherson seanjc@google.com
commit d5760dee127bf6f390b05e747369d7c37ae1a7b8 upstream.
WARN on and reject SEV commands that provide a valid data pointer, but do not have a known, non-zero length. And conversely, reject commands that take a command buffer but none is provided (data is null).
Aside from sanity checking input, disallowing a non-null pointer without a non-zero size will allow a future patch to cleanly handle vmalloc'd data by copying the data to an internal __pa() friendly buffer.
Note, this also effectively prevents callers from using commands that have a non-zero length and are not known to the kernel. This is not an explicit goal, but arguably the side effect is a good thing from the kernel's perspective.
Cc: Brijesh Singh brijesh.singh@amd.com Cc: Borislav Petkov bp@suse.de Cc: Tom Lendacky thomas.lendacky@amd.com Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20210406224952.4177376-4-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 Cc: Ben Hutchings benh@debian.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/crypto/ccp/sev-dev.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
--- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -156,6 +156,7 @@ static int __sev_do_cmd_locked(int cmd, struct sev_device *sev; unsigned int phys_lsb, phys_msb; unsigned int reg, ret = 0; + int buf_len;
if (!psp || !psp->sev_data) return -ENODEV; @@ -165,6 +166,10 @@ static int __sev_do_cmd_locked(int cmd,
sev = psp->sev_data;
+ buf_len = sev_cmd_buffer_len(cmd); + if (WARN_ON_ONCE(!data != !buf_len)) + return -EINVAL; + if (data && WARN_ON_ONCE(!virt_addr_valid(data))) return -EINVAL;
@@ -176,7 +181,7 @@ static int __sev_do_cmd_locked(int cmd, cmd, phys_msb, phys_lsb, psp_timeout);
print_hex_dump_debug("(in): ", DUMP_PREFIX_OFFSET, 16, 2, data, - sev_cmd_buffer_len(cmd), false); + buf_len, false);
iowrite32(phys_lsb, sev->io_regs + sev->vdata->cmdbuff_addr_lo_reg); iowrite32(phys_msb, sev->io_regs + sev->vdata->cmdbuff_addr_hi_reg); @@ -212,7 +217,7 @@ static int __sev_do_cmd_locked(int cmd, }
print_hex_dump_debug("(out): ", DUMP_PREFIX_OFFSET, 16, 2, data, - sev_cmd_buffer_len(cmd), false); + buf_len, false);
return ret; }