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From: Eugeniu Rosca <roscaeugeniu@gmail.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH v2 09/13] common.h: Fix signed shift overflow in cpumask_next()
Date: Mon, 27 Aug 2018 01:13:27 +0200	[thread overview]
Message-ID: <20180826231332.2491-10-erosca@de.adit-jv.com> (raw)
In-Reply-To: <20180826231332.2491-1-erosca@de.adit-jv.com>

Fix the following UBSAN report:
 =================================================================
 UBSAN: Undefined behaviour in include/common.h:322:19
 left shift of 1 by 31 places cannot be represented in type 'int'
 =================================================================

Steps to reproduce the above:
* echo CONFIG_UBSAN=y >> configs/qemu-ppce500_defconfig
* make ARCH=powerpc CROSS_COMPILE=/usr/bin/powerpc-linux-gnu- \
       qemu-ppce500_defconfig all
* qemu-system-ppc --version
  QEMU emulator version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.31)
* qemu-system-ppc -machine ppce500 -nographic -no-reboot -kernel u-boot

It looks like cpumask_next() intentionally uses shift overflow in its
for loop condition to break the loop. Relying on UB is not safe. Convert
the numeric literal 1 to 1UL and limit its maximum shift index to 31.

Fixes: fbb9ecf7493f ("powerpc/mp: add support for discontiguous cores")
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
---

Changes in v2:
 - None. Newly pushed.
---
 include/common.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/common.h b/include/common.h
index 940161f1758b..5b92666d0e79 100644
--- a/include/common.h
+++ b/include/common.h
@@ -319,7 +319,7 @@ void	trap_init     (ulong);
 /* $(CPU)/cpu.c */
 static inline int cpumask_next(int cpu, unsigned int mask)
 {
-	for (cpu++; !((1 << cpu) & mask); cpu++)
+	for (cpu++; (cpu < 31) && !((1UL << cpu) & mask); cpu++)
 		;
 
 	return cpu;
-- 
2.18.0

  parent reply	other threads:[~2018-08-26 23:13 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-26 23:13 [U-Boot] [PATCH v2 00/13] Import Undefined Behavior Sanitizer Eugeniu Rosca
2018-08-26 23:13 ` [U-Boot] [PATCH v2 01/13] UBSAN: run-time undefined behavior sanity checker Eugeniu Rosca
2018-08-27 14:13   ` Tom Rini
2018-08-26 23:13 ` [U-Boot] [PATCH v2 02/13] mmc: Fix signed shift overflow Eugeniu Rosca
2018-08-26 23:13 ` [U-Boot] [PATCH v2 03/13] armv8: mmu: " Eugeniu Rosca
2018-08-27 14:13   ` Tom Rini
2018-08-26 23:13 ` [U-Boot] [PATCH v2 04/13] pinctrl: renesas: " Eugeniu Rosca
2018-08-26 23:13 ` [U-Boot] [PATCH v2 05/13] net: phy: " Eugeniu Rosca
2018-08-26 23:13 ` [U-Boot] [PATCH v2 06/13] net: ravb: " Eugeniu Rosca
2018-08-26 23:22   ` Marek Vasut
2018-08-27 20:24     ` Eugeniu Rosca
2018-08-27 23:55       ` Marek Vasut
2018-08-26 23:13 ` [U-Boot] [PATCH v2 07/13] x86: Fix signed shift overflow in MSR_IA32_APICBASE_BASE Eugeniu Rosca
2018-08-28  2:05   ` Bin Meng
2018-08-28  6:42     ` Eugeniu Rosca
2018-09-01 10:59       ` Eugeniu Rosca
2018-09-04  4:00         ` Bin Meng
2018-09-16 18:46           ` Eugeniu Rosca
2018-09-22 23:10             ` Eugeniu Rosca
2018-09-25  2:06               ` Bin Meng
2018-10-09  0:22                 ` Eugeniu Rosca
2018-08-28  8:14     ` Andy Shevchenko
2018-08-26 23:13 ` [U-Boot] [PATCH v2 08/13] disk: part_dos: Fix signed shift overflow Eugeniu Rosca
2018-08-26 23:13 ` Eugeniu Rosca [this message]
2018-08-26 23:13 ` [U-Boot] [PATCH v2 10/13] mmc: Fix read-past-end-of-array Eugeniu Rosca
2018-08-26 23:13 ` [U-Boot] [PATCH v2 11/13] hashtable: Fix zero-sized array Eugeniu Rosca
2018-08-27 14:13   ` Tom Rini
2018-08-26 23:13 ` [U-Boot] [PATCH v2 12/13] input: " Eugeniu Rosca
2018-08-27 14:13   ` Tom Rini
2018-08-26 23:13 ` [U-Boot] [PATCH v2 13/13] configs: sandbox*: Enable UBSAN Eugeniu Rosca
2018-08-30  2:51   ` Simon Glass
2018-09-17 21:10     ` Eugeniu Rosca

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