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Message-Id: <20170814213732.104301-4-thgarnie@google.com>
Date: Mon, 14 Aug 2017 14:37:32 -0700
From: Thomas Garnier <thgarnie@...gle.com>
To: Al Viro <viro@...iv.linux.org.uk>,
Dave Hansen <dave.hansen@...el.com>,
Arnd Bergmann <arnd@...db.de>,
Thomas Gleixner <tglx@...utronix.de>,
Thomas Garnier <thgarnie@...gle.com>,
Yonghong Song <yhs@...com>,
David Howells <dhowells@...hat.com>,
Russell King <linux@...linux.org.uk>,
Kees Cook <keescook@...omium.org>,
Andy Lutomirski <luto@...capital.net>,
Will Drewry <wad@...omium.org>,
Dave Martin <Dave.Martin@....com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>
Cc: linux-api@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH v3 4/4] arm64/syscalls: Move address limit check in loop
A bug was reported on ARM where set_fs might be called after it was
checked on the work pending function. ARM64 is not affected by this bug
but has a similar construct. In order to avoid any similar problems in
the future, the addr_limit_user_check function is moved at the beginning
of the loop.
Fixes: cf7de27ab351 ("arm64/syscalls: Check address limit on user-mode return")
Reported-by: Leonard Crestez <leonard.crestez@....com>
Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
---
arch/arm64/kernel/signal.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index c45214f8fb54..0bdc96c61bc0 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -751,10 +751,10 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
*/
trace_hardirqs_off();
- /* Check valid user FS if needed */
- addr_limit_user_check();
-
do {
+ /* Check valid user FS if needed */
+ addr_limit_user_check();
+
if (thread_flags & _TIF_NEED_RESCHED) {
schedule();
} else {
--
2.14.1.480.gb18f417b89-goog
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