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From: James Morris <jmorris_at_intercode.com.au>
subject: [PATCH] safe memory allocation flags
Date: Thu, 6 Sep 2001 23:02:01 +1000 (EST)

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The patch below allows netdev_precondition() to be called safely from interrupt context.

This can occur, for example, in the IP networking input path, which runs under a softirq. Under these conditions, kernel memory needs to be allocated with the GFP_ATOMIC flag. If anyone has seen an oops upon network traffic immedately after booting, this may have been the cause.

• James -- James Morris <jmorris@intercode.com.au>

diff -urN -X /tmp/xmdiff module.orig/selinux_plug/hooks.c module/selinux_plug/hooks.c
--- module.orig/selinux_plug/hooks.c Thu Aug 23 14:20:50 2001
+++ module/selinux_plug/hooks.c Thu Sep 6 21:57:33 2001 @@ -308,7 +308,7 @@
 {

         struct netdev_security_struct *nsec = dev->security;

• nsec = kmalloc(sizeof(struct netdev_security_struct), GFP_KERNEL); + nsec = kmalloc(sizeof(struct netdev_security_struct), SAFE_ALLOC); if (!nsec) return -ENOMEM; memset(nsec, 0, sizeof(struct netdev_security_struct)); diff -urN -X /tmp/xmdiff module.orig/selinux_plug/include/linux/flask/flask_types.h module/selinux_plug/include/linux/flask/flask_types.h
  --- module.orig/selinux_plug/include/linux/flask/flask_types.h Thu Jul 19 06:38:10 2001
  +++ module/selinux_plug/include/linux/flask/flask_types.h Thu Sep 6 21:58:37 2001 @@ -76,5 +76,15 @@

 #define CUR_SID current->sid

+#ifdef __KERNEL__
+/*
+ * Use this for memory allocation flags (e.g. for kmalloc()) when the interrupt
+ * state is unknown.
+ */
+#include <linux/interrupt.h>
+
+#define SAFE_ALLOC (in_interrupt () ? GFP_ATOMIC : GFP_KERNEL)
+#endif
+

 #endif

diff -urN -X /tmp/xmdiff module.orig/selinux_plug/ss/global.h module/selinux_plug/ss/global.h
--- module.orig/selinux_plug/ss/global.h Thu Jul 19 06:38:07 2001
+++ module/selinux_plug/ss/global.h Thu Sep 6 22:19:22 2001 @@ -77,7 +77,7 @@
 #include <asm/uaccess.h>
 #include "selinux_plug.h"

-#define malloc(size) kmalloc(size, GFP_ATOMIC)
+#define malloc(size) kmalloc(size, SAFE_ALLOC)
 #define free(ptr) kfree(ptr)

 typedef struct file FILE;

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