[PATCH] x86/sgx: Initialize "ret" in sgx_ioc_enclave_add_pages()

[PATCH] x86/sgx: Initialize "ret" in sgx_ioc_enclave_add_pages()

[Jarkko Sakkinen]

Initialize "ret" to zero as otherwise a zero length address range will
leave it 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..36a244504da2 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -415,7 +415,7 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
 	struct sgx_enclave_add_pages add_arg;
 	struct sgx_secinfo secinfo;
 	unsigned long c;
-	int ret;
+	int ret = 0;
 
 	if (!test_bit(SGX_ENCL_CREATED, &encl->flags) ||
 	    test_bit(SGX_ENCL_INITIALIZED, &encl->flags))
-- 
2.27.0

Re: [PATCH] x86/sgx: Initialize "ret" in sgx_ioc_enclave_add_pages()

[Borislav Petkov]

On Wed, Dec 02, 2020 at 06:22:00PM +0200, Jarkko Sakkinen wrote:
> Initialize "ret" to zero as otherwise a zero length address range will
> leave it uninitialized.

That length is:

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

I think we wanna fail this even earlier when it wants to add data of
length 0 because that sounds nonsensical to me. Or is there some use
case for zero-length data?

Btw, pls CC lkml on patch submissions.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [PATCH] x86/sgx: Initialize "ret" in sgx_ioc_enclave_add_pages()

[Jarkko Sakkinen]

On Wed, Dec 02, 2020 at 06:38:29PM +0100, Borislav Petkov wrote:
> On Wed, Dec 02, 2020 at 06:22:00PM +0200, Jarkko Sakkinen wrote:
> > Initialize "ret" to zero as otherwise a zero length address range will
> > leave it uninitialized.
> 
> That length is:
> 
>  * @length:     length of the data (multiple of the page size)
> 
> I think we wanna fail this even earlier when it wants to add data of
> length 0 because that sounds nonsensical to me. Or is there some use
> case for zero-length data?
> 
> Btw, pls CC lkml on patch submissions.

Yeah, makes sense to fail right after copying the parameter struct
with -EINVAL.

> Thx.
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette
> 

/Jarkko