[PATCH] uml: Fix possible deadlock in sig_handler_common()

From: Richard Weinberger
Date: Sun Jun 12 2016 - 16:03:38 EST


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@xxxxxx>
---
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