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Message-Id: <20181209204449.18906-1-tycho@tycho.ws>
Date: Sun, 9 Dec 2018 13:44:49 -0700
From: Tycho Andersen <tycho@...ho.ws>
To: linux-sparse@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Cc: linux-kernel@...r.kernel.org,
Tycho Andersen <tycho@...ho.ws>
Subject: [RFC v1] copy_{to,from}_user(): only inline when !__CHECKER__
While working on some additional copy_to_user() checks for sparse, I
noticed that sparse's current copy_to_user() checks are not triggered. This
is because copy_to_user() is declared as __always_inline, and sparse
specifically looks for a call instruction to copy_to_user() when it tries
to apply the checks.
A quick fix is to explicitly not inline when __CHECKER__ is defined, so
that sparse will be able to analyze all the copy_{to,from}_user calls.
There may be some refactoring in sparse that we can do to fix this,
although it's not immediately obvious to me how, hence the RFC-ness of this
patch.
Signed-off-by: Tycho Andersen <tycho@...ho.ws>
---
include/linux/uaccess.h | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index efe79c1cdd47..f20a2d173e1f 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -140,7 +140,13 @@ extern unsigned long
_copy_to_user(void __user *, const void *, unsigned long);
#endif
-static __always_inline unsigned long __must_check
+#ifdef __CHECKER__
+#define uaccess_inline __attribute__((__noinline__))
+#else
+#define uaccess_inline __always_inline
+#endif
+
+static uaccess_inline unsigned long __must_check
copy_from_user(void *to, const void __user *from, unsigned long n)
{
if (likely(check_copy_size(to, n, false)))
@@ -148,7 +154,7 @@ copy_from_user(void *to, const void __user *from, unsigned long n)
return n;
}
-static __always_inline unsigned long __must_check
+static uaccess_inline unsigned long __must_check
copy_to_user(void __user *to, const void *from, unsigned long n)
{
if (likely(check_copy_size(from, n, true)))
--
2.19.1
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