Commit 8e00b2df authored by Alexander Potapenko's avatar Alexander Potapenko Committed by Andrew Morton

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.comSigned-off-by: default avatarAlexander Potapenko <glider@google.com>
Reported-by: default avatarsyzbot <syzkaller@googlegroups.com>
Reviewed-by: default avatarDmitry Vyukov <dvyukov@google.com>
Suggested-by: default avatarDmitry Vyukov <dvyukov@google.com>
Reviewed-by: default avatarAndrey Konovalov <andreyknvl@gmail.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 2178e20c
......@@ -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;
......
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