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[3/3] arm64/syscalls: Move address limit check in loop

Message ID 20170719175900.124074-3-thgarnie@google.com (mailing list archive)
State New, archived
Headers show

Commit Message

Thomas Garnier July 19, 2017, 5:59 p.m. UTC 
The original bug was reported on arm but I am fixing arm64 too because
it has a similar code pattern.

The work pending loop can call set_fs after addr_limit_user_check
removed the _TIF_FSCHECK flag. To prevent the infinite loop, move the
addr_limit_user_check call at the beginning of the loop.

Fixes: cf7de27ab351 ("arm64/syscalls: Check address limit on user-mode return")
Reported-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/arm64/kernel/signal.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
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Patch

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index e3e3293d1123..8e2705983e1d 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 {