diff mbox series

[1/3] x86/hyperv: allocate the hypercall page with only read and execute bits

Message ID 20200618064307.32739-2-hch@lst.de (mailing list archive)
State New, archived
Headers show
Series [1/3] x86/hyperv: allocate the hypercall page with only read and execute bits | expand

Commit Message

Christoph Hellwig June 18, 2020, 6:43 a.m. UTC 
Avoid a W^X violation cause by the fact that PAGE_KERNEL_EXEC includes the
writable bit.

For this resurrect the removed PAGE_KERNEL_RX definitіon, but as
PAGE_KERNEL_ROX to match arm64 and powerpc.

Fixes: 78bb17f76edc ("x86/hyperv: use vmalloc_exec for the hypercall page")
Reported-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/hyperv/hv_init.c            | 4 +++-
 arch/x86/include/asm/pgtable_types.h | 2 ++
 2 files changed, 5 insertions(+), 1 deletion(-)

Comments

Wei Liu June 18, 2020, 11:47 a.m. UTC | #1 
On Thu, Jun 18, 2020 at 08:43:05AM +0200, Christoph Hellwig wrote:
> Avoid a W^X violation cause by the fact that PAGE_KERNEL_EXEC includes the
> writable bit.
> 
> For this resurrect the removed PAGE_KERNEL_RX definitіon, but as
> PAGE_KERNEL_ROX to match arm64 and powerpc.
> 
> Fixes: 78bb17f76edc ("x86/hyperv: use vmalloc_exec for the hypercall page")
> Reported-by: Dexuan Cui <decui@microsoft.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Acked-by: Wei Liu <wei.liu@kernel.org>
diff mbox series

Patch

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index a54c6a401581dd..2bdc72e6890eca 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -375,7 +375,9 @@  void __init hyperv_init(void)
 	guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 	wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 
-	hv_hypercall_pg = vmalloc_exec(PAGE_SIZE);
+	hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
+			VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
+			VM_FLUSH_RESET_PERMS, NUMA_NO_NODE, __func__);
 	if (hv_hypercall_pg == NULL) {
 		wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 		goto remove_cpuhp_state;
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 2da1f95b88d761..816b31c685505f 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -194,6 +194,7 @@  enum page_cache_mode {
 #define _PAGE_TABLE_NOENC	 (__PP|__RW|_USR|___A|   0|___D|   0|   0)
 #define _PAGE_TABLE		 (__PP|__RW|_USR|___A|   0|___D|   0|   0| _ENC)
 #define __PAGE_KERNEL_RO	 (__PP|   0|   0|___A|__NX|___D|   0|___G)
+#define __PAGE_KERNEL_ROX	 (__PP|   0|   0|___A|   0|___D|   0|___G)
 #define __PAGE_KERNEL_NOCACHE	 (__PP|__RW|   0|___A|__NX|___D|   0|___G| __NC)
 #define __PAGE_KERNEL_VVAR	 (__PP|   0|_USR|___A|__NX|___D|   0|___G)
 #define __PAGE_KERNEL_LARGE	 (__PP|__RW|   0|___A|__NX|___D|_PSE|___G)
@@ -219,6 +220,7 @@  enum page_cache_mode {
 #define PAGE_KERNEL_RO		__pgprot_mask(__PAGE_KERNEL_RO         | _ENC)
 #define PAGE_KERNEL_EXEC	__pgprot_mask(__PAGE_KERNEL_EXEC       | _ENC)
 #define PAGE_KERNEL_EXEC_NOENC	__pgprot_mask(__PAGE_KERNEL_EXEC       |    0)
+#define PAGE_KERNEL_ROX		__pgprot_mask(__PAGE_KERNEL_ROX        | _ENC)
 #define PAGE_KERNEL_NOCACHE	__pgprot_mask(__PAGE_KERNEL_NOCACHE    | _ENC)
 #define PAGE_KERNEL_LARGE	__pgprot_mask(__PAGE_KERNEL_LARGE      | _ENC)
 #define PAGE_KERNEL_LARGE_EXEC	__pgprot_mask(__PAGE_KERNEL_LARGE_EXEC | _ENC)