linux-kernel - [PATCH] x86/sgx: Add xa_store_range() return value check in sgx_setup_epc

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Date:   Fri, 16 Sep 2022 00:50:06 +1200
From:   Kai Huang <kai.huang@...el.com>
To:     linux-sgx@...r.kernel.org
Cc:     dave.hansen@...ux.intel.com, jarkko@...nel.org,
        tony.luck@...el.com, linux-kernel@...r.kernel.org
Subject: [PATCH] x86/sgx: Add xa_store_range() return value check in sgx_setup_epc_section()

In sgx_setup_epc_section(), xa_store_range() is called to store EPC
pages' owner section to an Xarray using physical addresses of those EPC
pages as index.  Currently, the return value of xa_store_range() is not
checked, but actually it can fail (i.e. due to -ENOMEM).

Not checking the return value of xa_store_range() would result in the
EPC section being used by SGX driver (and KVM SGX guests), but part or
all of its EPC pages not being handled by the memory failure handling of
EPC page.  Such inconsistency should be avoided, even at the cost that
this section won't be used by the kernel.

Add the missing check of the return value of xa_store_range(), and when
it fails, clean up and fail to initialize the EPC section.

Fixes: 40e0e7843e23 ("x86/sgx: Add infrastructure to identify SGX EPC pages")
Signed-off-by: Kai Huang <kai.huang@...el.com>
---
 arch/x86/kernel/cpu/sgx/main.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 515e2a5f25bb..2ee23e60ef61 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -632,8 +632,12 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 	}

 	section->phys_addr = phys_addr;
-	xa_store_range(&sgx_epc_address_space, section->phys_addr,
-		       phys_addr + size - 1, section, GFP_KERNEL);
+	if (xa_err(xa_store_range(&sgx_epc_address_space, section->phys_addr,
+		       phys_addr + size - 1, section, GFP_KERNEL))) {
+		vfree(section->pages);
+		memunmap(section->virt_addr);
+		return false;
+	}

 	for (i = 0; i < nr_pages; i++) {
 		section->pages[i].section = index;

base-commit: ee56a283988d739c25d2d00ffb22707cb487ab47
-- 
2.37.1