From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Fix up the custom KASAN instrumentation for Shadow Call Stack to support
vmalloc() mappings and pointers being tagged.
- Use the tagged pointer returned by kasan_unpoison_vmalloc() in
__scs_alloc() when calling memset() to avoid false-positives.
- Do not return a tagged Shadow Call Stack pointer from __scs_alloc(),
as this might lead to conflicts with the instrumentation.
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
Andrew, please put this patch after
"kasan, vmalloc: only tag normal vmalloc allocations".
---
kernel/scs.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/kernel/scs.c b/kernel/scs.c
index 1033a76a3284..b7e1b096d906 100644
--- a/kernel/scs.c
+++ b/kernel/scs.c
@@ -32,16 +32,19 @@ 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_PROT_NORMAL);
+ s = kasan_unpoison_vmalloc(s, SCS_SIZE,
+ KASAN_VMALLOC_PROT_NORMAL);
memset(s, 0, SCS_SIZE);
- return s;
+ goto out;
}
}
- return __vmalloc_node_range(SCS_SIZE, 1, VMALLOC_START, VMALLOC_END,
+ s = __vmalloc_node_range(SCS_SIZE, 1, VMALLOC_START, VMALLOC_END,
GFP_SCS, PAGE_KERNEL, 0, node,
__builtin_return_address(0));
+
+out:
+ return kasan_reset_tag(s);
}
void *scs_alloc(int node)
--
2.25.1
