From: Catalin Marinas on
This is a fix for bug #14845 (bugzilla.kernel.org). The
update_checksum() function in mm/kmemleak.c calls
kmemcheck_is_obj_initialised() before scanning an object. When
KMEMCHECK_PARTIAL_OK is enabled, this function returns true. However,
the crc32_le() reads smaller intervals (32-bit) for which
kmemleak_is_obj_initialised() may be false leading to a kmemcheck
warning.

Note that kmemcheck_is_obj_initialized() is currently only used by
kmemleak before scanning a memory location.

Signed-off-by: Catalin Marinas <catalin.marinas(a)arm.com>
Cc: Andrew Morton <akpm(a)linux-foundation.org>
Cc: Christian Casteyde <casteyde.christian(a)free.fr>
Cc: Pekka Enberg <penberg(a)cs.helsinki.fi>
Cc: Vegard Nossum <vegardno(a)ifi.uio.no>
---
arch/x86/mm/kmemcheck/kmemcheck.c | 2 +-
arch/x86/mm/kmemcheck/shadow.c | 16 ++++++++++++++--
arch/x86/mm/kmemcheck/shadow.h | 2 ++
3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/kmemcheck/kmemcheck.c b/arch/x86/mm/kmemcheck/kmemcheck.c
index 8cc1833..b3b531a 100644
--- a/arch/x86/mm/kmemcheck/kmemcheck.c
+++ b/arch/x86/mm/kmemcheck/kmemcheck.c
@@ -337,7 +337,7 @@ bool kmemcheck_is_obj_initialized(unsigned long addr, size_t size)
if (!shadow)
return true;

- status = kmemcheck_shadow_test(shadow, size);
+ status = kmemcheck_shadow_test_all(shadow, size);

return status == KMEMCHECK_SHADOW_INITIALIZED;
}
diff --git a/arch/x86/mm/kmemcheck/shadow.c b/arch/x86/mm/kmemcheck/shadow.c
index 3f66b82..aec1242 100644
--- a/arch/x86/mm/kmemcheck/shadow.c
+++ b/arch/x86/mm/kmemcheck/shadow.c
@@ -125,12 +125,12 @@ void kmemcheck_mark_initialized_pages(struct page *p, unsigned int n)

enum kmemcheck_shadow kmemcheck_shadow_test(void *shadow, unsigned int size)
{
+#ifdef CONFIG_KMEMCHECK_PARTIAL_OK
uint8_t *x;
unsigned int i;

x = shadow;

-#ifdef CONFIG_KMEMCHECK_PARTIAL_OK
/*
* Make sure _some_ bytes are initialized. Gcc frequently generates
* code to access neighboring bytes.
@@ -139,13 +139,25 @@ enum kmemcheck_shadow kmemcheck_shadow_test(void *shadow, unsigned int size)
if (x[i] == KMEMCHECK_SHADOW_INITIALIZED)
return x[i];
}
+
+ return x[0];
#else
+ return kmemcheck_shadow_test_all(shadow, size);
+#endif
+}
+
+enum kmemcheck_shadow kmemcheck_shadow_test_all(void *shadow, unsigned int size)
+{
+ uint8_t *x;
+ unsigned int i;
+
+ x = shadow;
+
/* All bytes must be initialized. */
for (i = 0; i < size; ++i) {
if (x[i] != KMEMCHECK_SHADOW_INITIALIZED)
return x[i];
}
-#endif

return x[0];
}
diff --git a/arch/x86/mm/kmemcheck/shadow.h b/arch/x86/mm/kmemcheck/shadow.h
index af46d9a..ff0b2f7 100644
--- a/arch/x86/mm/kmemcheck/shadow.h
+++ b/arch/x86/mm/kmemcheck/shadow.h
@@ -11,6 +11,8 @@ enum kmemcheck_shadow {
void *kmemcheck_shadow_lookup(unsigned long address);

enum kmemcheck_shadow kmemcheck_shadow_test(void *shadow, unsigned int size);
+enum kmemcheck_shadow kmemcheck_shadow_test_all(void *shadow,
+ unsigned int size);
void kmemcheck_shadow_set(void *shadow, unsigned int size);

#endif

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