Patchwork [3.8.y.z,extended,stable] Patch "zram: avoid access beyond the zram device" has been added to staging queue

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Submitter Luis Henriques
Date July 9, 2013, 4:28 p.m.
Message ID <1373387284-20988-1-git-send-email-luis.henriques@canonical.com>
Download mbox | patch
Permalink /patch/257833/
State New
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Comments

Luis Henriques - July 9, 2013, 4:28 p.m.
This is a note to let you know that I have just added a patch titled

    zram: avoid access beyond the zram device

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

From ca0e16572c643ca7eab9e231f2dc3fbdce56ca92 Mon Sep 17 00:00:00 2001
From: Jiang Liu <liuj97@gmail.com>
Date: Fri, 7 Jun 2013 00:07:26 +0800
Subject: [PATCH] zram: avoid access beyond the zram device

commit 12a7ad3b810e77137d0caf97a6dd97591e075b30 upstream.

Function valid_io_request() should verify the entire request are within
the zram device address range. Otherwise it may cause invalid memory
access when accessing/modifying zram->meta->table[index] because the
'index' is out of range. Then it may access non-exist memory, randomly
modify memory belong to other subsystems, which is hard to track down.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/staging/zram/zram_drv.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

--
1.8.1.2

Patch

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index ff2228e..62f8276 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -461,13 +461,20 @@  out:
  */
 static inline int valid_io_request(struct zram *zram, struct bio *bio)
 {
-	if (unlikely(
-		(bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
-		(bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)) ||
-		(bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))) {
+	u64 start, end, bound;
+
+	/* unaligned request */
+	if (unlikely(bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
+		return 0;
+	if (unlikely(bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
+		return 0;

+	start = bio->bi_sector;
+	end = start + (bio->bi_size >> SECTOR_SHIFT);
+	bound = zram->disksize >> SECTOR_SHIFT;
+	/* out of range range */
+	if (unlikely(start >= bound || end >= bound || start > end))
 		return 0;
-	}

 	/* I/O request is valid */
 	return 1;