linux-kernel - [PATCH 4.4 066/105] zram: set physical queue limits to avoid array out of bounds accesses

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Message-Id: <20171215092309.317286005@linuxfoundation.org>
Date:   Fri, 15 Dec 2017 10:45:04 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Johannes Thumshirn <jthumshirn@...e.de>,
        Hannes Reinecke <hare@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Jens Axboe <axboe@...com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.4 066/105] zram: set physical queue limits to avoid array out of bounds accesses

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Thumshirn <jthumshirn@...e.de>


[ Upstream commit 0bc315381fe9ed9fb91db8b0e82171b645ac008f ]

zram can handle at most SECTORS_PER_PAGE sectors in a bio's bvec. When using
the NVMe over Fabrics loopback target which potentially sends a huge bulk of
pages attached to the bio's bvec this results in a kernel panic because of
array out of bounds accesses in zram_decompress_page().

Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>
Reviewed-by: Hannes Reinecke <hare@...e.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Signed-off-by: Jens Axboe <axboe@...com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/block/zram/zram_drv.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1247,6 +1247,8 @@ static int zram_add(void)
 	blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
 	blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
 	zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
+	zram->disk->queue->limits.max_sectors = SECTORS_PER_PAGE;
+	zram->disk->queue->limits.chunk_sectors = 0;
 	blk_queue_max_discard_sectors(zram->disk->queue, UINT_MAX);
 	/*
 	 * zram_bio_discard() will clear all logical blocks if logical block