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

The sgx_enclave_add_pages.length field is documented as

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

Fail with -EINVAL, when the caller gives a zero length buffer of data
to be added as pages to an enclave. Right now 'ret' is returned as
uninitialized in that case.

 [ bp: Flesh out commit message. ]

Fixes: c6d26d370767 ("x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES")
Reported-by: Dan Carpenter <[email protected]>
Signed-off-by: Jarkko Sakkinen <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Link: https://lore.kernel.org/linux-sgx/X8ehQssnslm194ld@mwanda/
Link: https://lkml.kernel.org/r/[email protected]

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index c206aee80a04f8720f788f1c4bd20679c6df7f0c..90a5caf76939a7bc71423ea98b5bc7254c1c1261 100644 (file)
--- 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)