linux-kernel - [PATCH v8 05/11] arm: snapshot thread flags

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-Id: <20211129130653.2037928-6-mark.rutland@arm.com>
Date:   Mon, 29 Nov 2021 13:06:47 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     linux-kernel@...r.kernel.org
Cc:     benh@...nel.crashing.org, boqun.feng@...il.com, bp@...en8.de,
        catalin.marinas@....com, dvyukov@...gle.com, efuller@...hat.com,
        elver@...gle.com, ink@...assic.park.msu.ru, jonas@...thpole.se,
        juri.lelli@...hat.com, linux@...linux.org.uk, luto@...nel.org,
        mark.rutland@....com, mattst88@...il.com, michal.simek@...inx.com,
        mingo@...hat.com, mpe@...erman.id.au, npiggin@...il.com,
        paulmck@...nel.org, paulus@...ba.org, peterz@...radead.org,
        rth@...ddle.net, shorne@...il.com,
        stefan.kristiansson@...nalahti.fi, tglx@...utronix.de,
        vincent.guittot@...aro.org, will@...nel.org
Subject: [PATCH v8 05/11] arm: snapshot thread flags

Some thread flags can be set remotely, and so even when IRQs are
disabled, the flags can change under our feet. Generally this is
unlikely to cause a problem in practice, but it is somewhat unsound, and
KCSAN will legitimately warn that there is a data race.

To avoid such issues, a snapshot of the flags has to be taken prior to
using them. Some places already use READ_ONCE() for that, others do not.

Convert them all to the new flag accessor helpers.

Signed-off-by: Mark Rutland <mark.rutland@....com>
Acked-by: Paul E. McKenney <paulmck@...nel.org>
Cc: Russell King <linux@...linux.org.uk>
---
 arch/arm/kernel/signal.c | 2 +-
 arch/arm/mm/alignment.c  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index a41e27ace391..c532a6041066 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -631,7 +631,7 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 			}
 		}
 		local_irq_disable();
-		thread_flags = current_thread_info()->flags;
+		thread_flags = read_thread_flags();
 	} while (thread_flags & _TIF_WORK_MASK);
 	return 0;
 }
diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index ea81e89e7740..adbb3817d0be 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -990,7 +990,7 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 		 * there is no work pending for this thread.
 		 */
 		raw_local_irq_disable();
-		if (!(current_thread_info()->flags & _TIF_WORK_MASK))
+		if (!(read_thread_flags() & _TIF_WORK_MASK))
 			set_cr(cr_no_alignment);
 	}
 
-- 
2.30.2