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authorAlexander Potapenko <glider@google.com>2023-03-06 12:13:21 +0100
committerAndrew Morton <akpm@linux-foundation.org>2023-03-28 16:20:13 -0700
commit8e00b2dffd822b34d8d1c627dc19f0743f9f5ac6 (patch)
tree662a4fb4742101a09a19956623efb3dbbeffa7ac /lib
parent2178e20c24406548c97b18a2d9781d16c35b8881 (diff)
lib/stackdepot: kmsan: mark API outputs as initialized
KMSAN does not instrument stackdepot and may treat memory allocated by it as uninitialized. This is not a problem for KMSAN itself, because its functions calling stackdepot API are also not instrumented. But other kernel features (e.g. netdev tracker) may access stack depot from instrumented code, which will lead to false positives, unless we explicitly mark stackdepot outputs as initialized. Link: https://lkml.kernel.org/r/20230306111322.205724-1-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Suggested-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Cc: Marco Elver <elver@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/stackdepot.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 036da8e295d1..2f5aa851834e 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -17,6 +17,7 @@
#include <linux/gfp.h>
#include <linux/jhash.h>
#include <linux/kernel.h>
+#include <linux/kmsan.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/percpu.h>
@@ -306,6 +307,11 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc)
stack->handle.extra = 0;
memcpy(stack->entries, entries, flex_array_size(stack, entries, size));
pool_offset += required_size;
+ /*
+ * Let KMSAN know the stored stack record is initialized. This shall
+ * prevent false positive reports if instrumented code accesses it.
+ */
+ kmsan_unpoison_memory(stack, required_size);
return stack;
}
@@ -465,6 +471,12 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
struct stack_record *stack;
*entries = NULL;
+ /*
+ * Let KMSAN know *entries is initialized. This shall prevent false
+ * positive reports if instrumented code accesses it.
+ */
+ kmsan_unpoison_memory(entries, sizeof(*entries));
+
if (!handle)
return 0;