linux-kernel - [PATCH] uml: Fix possible deadlock in sig_handler

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Message-Id: <1465761796-26950-1-git-send-email-richard@nod.at>
Date:	Sun, 12 Jun 2016 22:03:16 +0200
From:	Richard Weinberger <richard@....at>
To:	user-mode-linux-devel@...ts.sourceforge.net
Cc:	linux-kernel@...r.kernel.org, hwhilse@...il.com, elicooper@....com,
	thomas@...3r.de, aivanov@...cade.com,
	Richard Weinberger <richard@....at>
Subject: [PATCH] uml: Fix possible deadlock in sig_handler_common()

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

Signed-off-by: Richard Weinberger <richard@....at>
---
 arch/um/os-Linux/signal.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 8acaf4e..a86d7cc 100644
--- 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 siginfo *si, mcontext_t *mc)
 	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(mcontext_t *mc)
 {
 	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");
 
-- 
2.7.3