linux-kernel - [PATCH] kexec: avoid freeing NULL pointer in function kimage_crash

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Date:	Fri, 22 Feb 2013 12:50:50 +0800
From:	Zhang Yanfei <zhangyanfei@...fujitsu.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] kexec: avoid freeing NULL pointer in function kimage_crash_alloc

Though there is no error if we free a NULL pointer, I think we could
avoid this behaviour. Change the code a little in kimage_crash_alloc()
could avoid this kind of unnecessary free.

Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Zhang Yanfei <zhangyanfei@...fujitsu.com>
---
 kernel/kexec.c |   15 +++++++--------
 1 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/kernel/kexec.c b/kernel/kexec.c
index 5e4bd78..4e96fa7 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -310,7 +310,7 @@ static int kimage_crash_alloc(struct kimage **rimage, unsigned long entry,
 		mend = mstart + image->segment[i].memsz - 1;
 		/* Ensure we are within the crash kernel limits */
 		if ((mstart < crashk_res.start) || (mend > crashk_res.end))
-			goto out;
+			goto out_free;
 	}
 
 	/*
@@ -323,16 +323,15 @@ static int kimage_crash_alloc(struct kimage **rimage, unsigned long entry,
 					   get_order(KEXEC_CONTROL_PAGE_SIZE));
 	if (!image->control_code_page) {
 		printk(KERN_ERR "Could not allocate control_code_buffer\n");
-		goto out;
+		goto out_free;
 	}
 
-	result = 0;
-out:
-	if (result == 0)
-		*rimage = image;
-	else
-		kfree(image);
+	*rimage = image;
+	return 0;
 
+out_free:
+	kfree(image);
+out:
 	return result;
 }
 
-- 
1.7.1
--
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