linux-kernel - [PATCH v4] bitops: Fix shift overflow in GENMASK macros

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1415267659-10563-1-git-send-email-maxime.coquelin@st.com>
Date:	Thu,  6 Nov 2014 10:54:19 +0100
From:	Maxime COQUELIN <maxime.coquelin@...com>
To:	linux@...musvillemoes.dk, gong.chen@...ux.intel.com,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	" Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, tytso@....edu,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	kernel@...inux.com, maxime.coquelin@...com, eric.paire@...com
Subject: [PATCH v4] bitops: Fix shift overflow in GENMASK macros

On some 32 bits architectures, including x86, GENMASK(31, 0) returns 0
instead of the expected ~0UL.

This is the same on some 64 bits architectures with GENMASK_ULL(63, 0).

This is due to an overflow in the shift operand, 1 << 32 for GENMASK,
1 << 64 for GENMASK_ULL.

Fixes: 10ef6b0dffe404bcc54e94cb2ca1a5b18445a66b
Cc: <stable@...r.kernel.org> #v3.13+
Reported-by: Eric Paire <eric.paire@...com>
Suggested-by: Rasmus Villemoes <linux@...musvillemoes.dk>
Signed-off-by: Maxime Coquelin <maxime.coquelin@...com>
---
 include/linux/bitops.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index be5fd38..5d858e0 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -18,8 +18,11 @@
  * position @h. For example
  * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
  */
-#define GENMASK(h, l)		(((U32_C(1) << ((h) - (l) + 1)) - 1) << (l))
-#define GENMASK_ULL(h, l)	(((U64_C(1) << ((h) - (l) + 1)) - 1) << (l))
+#define GENMASK(h, l) \
+	(((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
+
+#define GENMASK_ULL(h, l) \
+	(((~0ULL) << (l)) & (~0ULL >> (BITS_PER_LONG_LONG - 1 - (h))))
 
 extern unsigned int __sw_hweight8(unsigned int w);
 extern unsigned int __sw_hweight16(unsigned int w);
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/