From: Chris Metcalf <cmetcalf@ezchip.com>
To: Andrew Morton <akpm@linux-foundation.org>,
        Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>,
        Pekka Enberg <penberg@kernel.org>,
        "Paul McQuade" <paulmcquad@gmail.com>,
        Tang Chen <tangchen@cn.fujitsu.com>, "Mel Gorman" <mgorman@suse.de>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
CC: Chris Metcalf <cmetcalf@ezchip.com>
Subject: [PATCH] bootmem: avoid freeing to bootmem after bootmem is done
Date: Fri, 24 Jul 2015 16:53:46 -0400
Message-ID: <1437771226-31255-1-git-send-email-cmetcalf@ezchip.com>
MIME-Version: 1.0
Content-Type: text/plain
DB5PR02MB0775: X-MS-Exchange-Organization-RulesExecuted
SpamDiagnosticOutput: 1:23
SpamDiagnosticMetadata: NSPM
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Jul 2015 20:53:51.7764
 (UTC)
X-MS-Exchange-CrossTenant-Id: 0fc16e0a-3cd3-4092-8b2f-0a42cff122c3
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=0fc16e0a-3cd3-4092-8b2f-0a42cff122c3;Ip=[12.216.194.146];Helo=[ld-1.internal.tilera.com]
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB5PR02MB0775
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1771
Lines: 53

Bootmem isn't popular any more, but some architectures still use
it, and freeing to bootmem after calling free_all_bootmem_core()
can end up scribbling over random memory.  Instead, make sure the
kernel panics by ensuring the node_bootmem_map field is non-NULL
when are freeing or marking bootmem.

An instance of this bug was just fixed in the tile architecture
("tile: use free_bootmem_late() for initrd") and catching this case
more widely seems like a good thing.

Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
---
 mm/bootmem.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/bootmem.c b/mm/bootmem.c
index a23dd1934654..178748259736 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -236,6 +236,7 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
 	count += pages;
 	while (pages--)
 		__free_pages_bootmem(page++, cur++, 0);
+	bdata->node_bootmem_map = NULL;
 
 	bdebug("nid=%td released=%lx\n", bdata - bootmem_node_data, count);
 
@@ -294,6 +295,8 @@ static void __init __free(bootmem_data_t *bdata,
 		sidx + bdata->node_min_pfn,
 		eidx + bdata->node_min_pfn);
 
+	BUG_ON(bdata->node_bootmem_map == NULL);
+
 	if (bdata->hint_idx > sidx)
 		bdata->hint_idx = sidx;
 
@@ -314,6 +317,8 @@ static int __init __reserve(bootmem_data_t *bdata, unsigned long sidx,
 		eidx + bdata->node_min_pfn,
 		flags);
 
+	BUG_ON(bdata->node_bootmem_map == NULL);
+
 	for (idx = sidx; idx < eidx; idx++)
 		if (test_and_set_bit(idx, bdata->node_bootmem_map)) {
 			if (exclusive) {
-- 
2.1.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/