linux-kernel - [PATCH 16/15] kexec: Fix freeing up for image loader data loading

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Date:	Fri, 27 Jun 2014 12:34:23 -0400
From:	Vivek Goyal <vgoyal@...hat.com>
To:	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org
Cc:	ebiederm@...ssion.com, hpa@...or.com, mjg59@...f.ucam.org,
	greg@...ah.com, bp@...en8.de, dyoung@...hat.com,
	chaowang@...hat.com, bhe@...hat.com, akpm@...ux-foundation.org
Subject: [PATCH 16/15] kexec: Fix freeing up for image loader data loading


During testing I noticed a crash. Which in turn showed that there are
problems with how I am freeing up image->image_loader_data.

In one case I am freeing up kimage->image_loader_data first and then
calling up arch to free up which might have been contained in that
structure. That's wrong.

I have done little cleanup and this should fix the issues around
freeing up of loader data.

Signed-off-by: Vivek Goyal <vgoyal@...hat.com>
---
 arch/x86/kernel/kexec-bzimage64.c  |    4 ++--
 arch/x86/kernel/machine_kexec_64.c |    2 +-
 include/linux/kexec.h              |    2 +-
 kernel/kexec.c                     |   11 ++++++++---
 4 files changed, 12 insertions(+), 7 deletions(-)

Index: linux-2.6/arch/x86/kernel/machine_kexec_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/machine_kexec_64.c	2014-06-27 09:55:41.824755401 -0400
+++ linux-2.6/arch/x86/kernel/machine_kexec_64.c	2014-06-27 11:02:02.607548946 -0400
@@ -369,7 +369,7 @@ int arch_kimage_file_post_load_cleanup(s
 	if (!image->fops || !image->fops->cleanup)
 		return 0;
 
-	return image->fops->cleanup(image);
+	return image->fops->cleanup(image->image_loader_data);
 }
 
 /*
Index: linux-2.6/include/linux/kexec.h
===================================================================
--- linux-2.6.orig/include/linux/kexec.h	2014-06-27 09:55:41.695754029 -0400
+++ linux-2.6/include/linux/kexec.h	2014-06-27 11:04:28.467151813 -0400
@@ -190,7 +190,7 @@ typedef void *(kexec_load_t)(struct kima
 			     unsigned long kernel_len, char *initrd,
 			     unsigned long initrd_len, char *cmdline,
 			     unsigned long cmdline_len);
-typedef int (kexec_cleanup_t)(struct kimage *image);
+typedef int (kexec_cleanup_t)(void *loader_data);
 
 struct kexec_file_ops {
 	kexec_probe_t *probe;
Index: linux-2.6/arch/x86/kernel/kexec-bzimage64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/kexec-bzimage64.c	2014-06-27 09:55:41.872755912 -0400
+++ linux-2.6/arch/x86/kernel/kexec-bzimage64.c	2014-06-27 11:05:42.151963710 -0400
@@ -512,9 +512,9 @@ out_free_params:
 }
 
 /* This cleanup function is called after various segments have been loaded */
-int bzImage64_cleanup(struct kimage *image)
+int bzImage64_cleanup(void *loader_data)
 {
-	struct bzimage64_data *ldata = image->image_loader_data;
+	struct bzimage64_data *ldata = loader_data;
 
 	if (!ldata)
 		return 0;
Index: linux-2.6/kernel/kexec.c
===================================================================
--- linux-2.6.orig/kernel/kexec.c	2014-06-27 10:04:23.409024171 -0400
+++ linux-2.6/kernel/kexec.c	2014-06-27 11:45:14.684874978 -0400
@@ -459,6 +459,14 @@ static void kimage_file_post_load_cleanu
 
 	/* See if architecture has anything to cleanup post load */
 	arch_kimage_file_post_load_cleanup(image);
+
+	/*
+	 * Above call should have called into bootloader to free up
+	 * any data stored in kimage->image_loader_data. It should
+	 * be ok now to free it up.
+	 */
+	kfree(image->image_loader_data);
+	image->image_loader_data = NULL;
 }
 
 /*
@@ -584,7 +592,6 @@ out_free_control_pages:
 	kimage_free_page_list(&image->control_pages);
 out_free_post_load_bufs:
 	kimage_file_post_load_cleanup(image);
-	kfree(image->image_loader_data);
 out_free_image:
 	kfree(image);
 	return ret;
@@ -908,8 +915,6 @@ static void kimage_free(struct kimage *i
 	/* Free the kexec control pages... */
 	kimage_free_page_list(&image->control_pages);
 
-	kfree(image->image_loader_data);
-
 	/*
 	 * Free up any temporary buffers allocated. This might hit if
 	 * error occurred much later after buffer allocation.
--
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