[PATCH mm 1/2] fix for "kasan, vmalloc: only tag normal vmalloc allocations"

From: andrey . konovalov
Date: Wed Mar 02 2022 - 10:13:44 EST


From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>

Pass KASAN_VMALLOC_PROT_NORMAL to kasan_unpoison_vmalloc() in the custom
KASAN instrumentation for Shadow Call Stack, as Shadow Call Stack mappings
are not executable and thus can be poisoned.

Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
kernel/scs.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/scs.c b/kernel/scs.c
index b83bc9251f99..1033a76a3284 100644
--- a/kernel/scs.c
+++ b/kernel/scs.c
@@ -32,7 +32,8 @@ static void *__scs_alloc(int node)
for (i = 0; i < NR_CACHED_SCS; i++) {
s = this_cpu_xchg(scs_cache[i], NULL);
if (s) {
- kasan_unpoison_vmalloc(s, SCS_SIZE, KASAN_VMALLOC_NONE);
+ kasan_unpoison_vmalloc(s, SCS_SIZE,
+ KASAN_VMALLOC_PROT_NORMAL);
memset(s, 0, SCS_SIZE);
return s;
}
@@ -78,7 +79,7 @@ void scs_free(void *s)
if (this_cpu_cmpxchg(scs_cache[i], 0, s) == NULL)
return;

- kasan_unpoison_vmalloc(s, SCS_SIZE, KASAN_VMALLOC_NONE);
+ kasan_unpoison_vmalloc(s, SCS_SIZE, KASAN_VMALLOC_PROT_NORMAL);
vfree_atomic(s);
}

--
2.25.1