linux-kernel - [PATCH 4.7 170/186] um: Fix possible deadlock in sig_handler

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Date:	Thu, 18 Aug 2016 15:59:47 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Richard Weinberger <richard@....at>
Subject: [PATCH 4.7 170/186] um: Fix possible deadlock in sig_handler_common()

4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Richard Weinberger <richard@....at>

commit 57a05d83b16710aff30510c33768df7ab17e0b4a upstream.

We are in atomic context and must not sleep.
Sleeping here is possible since malloc() maps
to kmalloc() with GFP_KERNEL.

Fixes: b6024b21 ("um: extend fpstate to _xstate to support YMM registers")
Signed-off-by: Richard Weinberger <richard@....at>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/um/os-Linux/signal.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -15,6 +15,7 @@
 #include <kern_util.h>
 #include <os.h>
 #include <sysdep/mcontext.h>
+#include <um_malloc.h>
 
 void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = {
 	[SIGTRAP]	= relay_signal,
@@ -32,7 +33,7 @@ static void sig_handler_common(int sig,
 	struct uml_pt_regs *r;
 	int save_errno = errno;
 
-	r = malloc(sizeof(struct uml_pt_regs));
+	r = uml_kmalloc(sizeof(struct uml_pt_regs), UM_GFP_ATOMIC);
 	if (!r)
 		panic("out of memory");
 
@@ -91,7 +92,7 @@ static void timer_real_alarm_handler(mco
 {
 	struct uml_pt_regs *regs;
 
-	regs = malloc(sizeof(struct uml_pt_regs));
+	regs = uml_kmalloc(sizeof(struct uml_pt_regs), UM_GFP_ATOMIC);
 	if (!regs)
 		panic("out of memory");