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From: Jonathan Steel <jon.steel@esentire.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH] kexec, kernel 2.6.26.5, segmentation fault in kimage_add_entry
Date: Tue, 16 Sep 2008 15:18:23 -0400	[thread overview]
Message-ID: <48D0067F.3020007@esentire.com> (raw)

A segmentation fault can occur in kimage_add_entry in kexec.c when 
loading a kernel image into memory. The fault occurs because a page is 
requested by calling kimage_alloc_page with gfp_mask GFP_KERNEL and the 
function may actually return a page with gfp_mask GFP_HIGHUSER. The high 
mem page is returned because it was swapped with the kernel page due to 
the kernel page being a page that will shortly be copied to.

This patch ensures that kimage_alloc_page returns a page that was 
created with the correct gfp flags.

--- linux-2.6.26.5.orig/kernel/kexec.c    2008-09-16 13:17:56.000000000 
-0400
+++ linux-2.6.26.5/kernel/kexec.c    2008-09-16 13:26:35.000000000 -0400
@@ -743,8 +743,15 @@ static struct page *kimage_alloc_page(st
             *old = addr | (*old & ~PAGE_MASK);
 
             /* The old page I have found cannot be a
-             * destination page, so return it.
-             */
+             * destination page, so return it if its
+             * gfp_flags honor the ones passed in.
+            */
+            if (!(gfp_mask & __GFP_HIGHMEM) &&
+                    PageHighMem(old_page)) {
+                kimage_free_pages(old_page);
+                continue;
+            }
+
             addr = old_addr;
             page = old_page;
             break;

Signed-off-by: Jonathan Steel <jon.steel@esentire.com>

Jonathan Steel

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kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

WARNING: multiple messages have this Message-ID (diff)
From: Jonathan Steel <jon.steel@esentire.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH] kexec, kernel 2.6.26.5, segmentation fault in kimage_add_entry
Date: Tue, 16 Sep 2008 15:18:23 -0400	[thread overview]
Message-ID: <48D0067F.3020007@esentire.com> (raw)

A segmentation fault can occur in kimage_add_entry in kexec.c when 
loading a kernel image into memory. The fault occurs because a page is 
requested by calling kimage_alloc_page with gfp_mask GFP_KERNEL and the 
function may actually return a page with gfp_mask GFP_HIGHUSER. The high 
mem page is returned because it was swapped with the kernel page due to 
the kernel page being a page that will shortly be copied to.

This patch ensures that kimage_alloc_page returns a page that was 
created with the correct gfp flags.

--- linux-2.6.26.5.orig/kernel/kexec.c    2008-09-16 13:17:56.000000000 
-0400
+++ linux-2.6.26.5/kernel/kexec.c    2008-09-16 13:26:35.000000000 -0400
@@ -743,8 +743,15 @@ static struct page *kimage_alloc_page(st
             *old = addr | (*old & ~PAGE_MASK);
 
             /* The old page I have found cannot be a
-             * destination page, so return it.
-             */
+             * destination page, so return it if its
+             * gfp_flags honor the ones passed in.
+            */
+            if (!(gfp_mask & __GFP_HIGHMEM) &&
+                    PageHighMem(old_page)) {
+                kimage_free_pages(old_page);
+                continue;
+            }
+
             addr = old_addr;
             page = old_page;
             break;

Signed-off-by: Jonathan Steel <jon.steel@esentire.com>

Jonathan Steel

             reply	other threads:[~2008-09-16 19:18 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-16 19:18 Jonathan Steel [this message]
2008-09-16 19:18 ` [PATCH] kexec, kernel 2.6.26.5, segmentation fault in kimage_add_entry Jonathan Steel
2008-09-16 22:21 ` [PATCH] kexec: " Eric W. Biederman
2008-09-16 22:21   ` Eric W. Biederman
2008-09-18  4:30   ` Simon Horman
2008-09-18  4:30     ` Simon Horman
2008-09-17  0:55 ` [PATCH] kexec, kernel 2.6.26.5, " Simon Horman
2008-09-17  0:55   ` Simon Horman
2008-09-17  2:40   ` Eric W. Biederman
2008-09-17  2:40     ` Eric W. Biederman
2008-09-17 13:18   ` Jonathan Steel
2008-09-17 13:18     ` Jonathan Steel

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