[PATCH 1/2] ARM: ioremap: Flush PGDs for VMALLOC shadow

[Linus Walleij]

When sync:ing the VMALLOC area to other CPUs, make sure to also
sync the KASAN shadow memory for the VMALLOC area, so that we
don't get stale entries for the shadow memory in the top level PGD.

Cc: stable at vger.kernel.org
Fixes: 565cbaad83d8 ("ARM: 9202/1: kasan: support CONFIG_KASAN_VMALLOC")
Link: https://lore.kernel.org/linux-arm-kernel/a1a1d062-f3a2-4d05-9836-3b098de9db6d@foss.st.com/
Reported-by: Clement LE GOFFIC <clement.legoffic at foss.st.com>
Suggested-by: Mark Rutland <mark.rutland at arm.com>
Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
---
 arch/arm/mm/ioremap.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index 794cfea9f9d4..449f1f04814c 100644
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -23,6 +23,7 @@
  */
 #include <linux/module.h>
 #include <linux/errno.h>
+#include <linux/kasan.h>
 #include <linux/mm.h>
 #include <linux/vmalloc.h>
 #include <linux/io.h>
@@ -125,6 +126,12 @@ void __check_vmalloc_seq(struct mm_struct *mm)
 		       pgd_offset_k(VMALLOC_START),
 		       sizeof(pgd_t) * (pgd_index(VMALLOC_END) -
 					pgd_index(VMALLOC_START)));
+		if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
+			memcpy(pgd_offset(mm, (unsigned long)kasan_mem_to_shadow((void *)VMALLOC_START)),
+			       pgd_offset_k((unsigned long)kasan_mem_to_shadow((void *)VMALLOC_START)),
+			       sizeof(pgd_t) * (pgd_index((unsigned long)kasan_mem_to_shadow((void *)VMALLOC_END)) -
+						pgd_index((unsigned long)kasan_mem_to_shadow((void *)VMALLOC_START))));
+		}
 		/*
 		 * Use a store-release so that other CPUs that observe the
 		 * counter's new value are guaranteed to see the results of the

-- 
2.46.2