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Subject[PATCH] x86: Remove unnecessary kmap() from sgx_ioc_enclave_init()
Date
From: Ira Weiny <ira.weiny@intel.com>

There is no reason to alloc a page and kmap it to store this temporary
data from the user. This is especially true when we are trying to
remove kmap usages. Also placing the token pointer 1/2 way into the
page is fragile.

Replace this allocation with two kzalloc()'s which also removes the need
for the memset().

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
arch/x86/kernel/cpu/sgx/ioctl.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 90a5caf76939..9c9019760585 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -604,7 +604,6 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg)
{
struct sgx_sigstruct *sigstruct;
struct sgx_enclave_init init_arg;
- struct page *initp_page;
void *token;
int ret;

@@ -615,13 +614,15 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg)
if (copy_from_user(&init_arg, arg, sizeof(init_arg)))
return -EFAULT;

- initp_page = alloc_page(GFP_KERNEL);
- if (!initp_page)
+ sigstruct = kzalloc(sizeof(*sigstruct), GFP_KERNEL);
+ if (!sigstruct)
return -ENOMEM;

- sigstruct = kmap(initp_page);
- token = (void *)((unsigned long)sigstruct + PAGE_SIZE / 2);
- memset(token, 0, SGX_LAUNCH_TOKEN_SIZE);
+ token = kzalloc(SGX_LAUNCH_TOKEN_SIZE, GFP_KERNEL);
+ if (!token) {
+ ret = -ENOMEM;
+ goto free_sigstruct;
+ }

if (copy_from_user(sigstruct, (void __user *)init_arg.sigstruct,
sizeof(*sigstruct))) {
@@ -645,8 +646,9 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg)
ret = sgx_encl_init(encl, sigstruct, token);

out:
- kunmap(initp_page);
- __free_page(initp_page);
+ kfree(token);
+free_sigstruct:
+ kfree(sigstruct);
return ret;
}

--
2.28.0.rc0.12.gb6a658bd00c9
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