[PATCH] x86/sgx: Return -EINVAL on a zero length buffer in sgx_ioc_enclave_add_pages()

[Jarkko Sakkinen <jarkko@kernel.org>]

The length documented as

 * @length:     length of the data (multiple of the page size)

Fail with -EINVAL, when user gives a zero length buffer. Right now
'ret' is returned as uninitialized.

Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lore.kernel.org/linux-sgx/X8ehQssnslm194ld@mwanda/
Fixes: c6d26d370767 ("x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 arch/x86/kernel/cpu/sgx/ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index c206aee80a04..90a5caf76939 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -428,7 +428,7 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
 	    !IS_ALIGNED(add_arg.src, PAGE_SIZE))
 		return -EINVAL;
 
-	if (add_arg.length & (PAGE_SIZE - 1))
+	if (!add_arg.length || add_arg.length & (PAGE_SIZE - 1))
 		return -EINVAL;
 
 	if (add_arg.offset + add_arg.length - PAGE_SIZE >= encl->size)
-- 
2.27.0