[36/43] x86: kmsan: sync metadata pages on page fault

Commit Message

Alexander Potapenko Dec. 14, 2021, 4:20 p.m. UTC

KMSAN assumes shadow and origin pages for every allocated page are
accessible. For pages between [VMALLOC_START, VMALLOC_END] those metadata
pages start at KMSAN_VMALLOC_SHADOW_START and
KMSAN_VMALLOC_ORIGIN_START, therefore we must sync a bigger memory
region.

Signed-off-by: Alexander Potapenko <[e-mail]>

---

Link: https://linux-review.googlesource.com/id/Ia5bd541e54f1ecc11b86666c3ec87c62ac0bdfb8
---
 arch/x86/mm/fault.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

Patch

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 4bfed53e210ec..abed0aedf00d2 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -260,7 +260,7 @@  static noinline int vmalloc_fault(unsigned long address)
 }
 NOKPROBE_SYMBOL(vmalloc_fault);
 
-void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
+void __arch_sync_kernel_mappings(unsigned long start, unsigned long end)
 {
 	unsigned long addr;
 
@@ -284,6 +284,26 @@  void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
 	}
 }
 
+void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
+{
+	__arch_sync_kernel_mappings(start, end);
+	/*
+	 * KMSAN maintains two additional metadata page mappings for the
+	 * [VMALLOC_START, VMALLOC_END) range. These mappings start at
+	 * KMSAN_VMALLOC_SHADOW_START and KMSAN_VMALLOC_ORIGIN_START and
+	 * have to be synced together with the vmalloc memory mapping.
+	 */
+	if (IS_ENABLED(CONFIG_KMSAN) &&
+	    start >= VMALLOC_START && end < VMALLOC_END) {
+		__arch_sync_kernel_mappings(
+			start - VMALLOC_START + KMSAN_VMALLOC_SHADOW_START,
+			end - VMALLOC_START + KMSAN_VMALLOC_SHADOW_START);
+		__arch_sync_kernel_mappings(
+			start - VMALLOC_START + KMSAN_VMALLOC_ORIGIN_START,
+			end - VMALLOC_START + KMSAN_VMALLOC_ORIGIN_START);
+	}
+}
+
 static bool low_pfn(unsigned long pfn)
 {
 	return pfn < max_low_pfn;