From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 7 Jun 2013 17:09:45 +0900 From: Minchan Kim To: Jiang Liu Cc: Greg Kroah-Hartman , Nitin Gupta , Jerome Marchand , Jiang Liu , devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v3 05/10] zram: avoid access beyond the zram device Message-ID: <20130607080945.GD22516@blaptop> References: <1370534851-26056-1-git-send-email-jiang.liu@huawei.com> <1370534851-26056-6-git-send-email-jiang.liu@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1370534851-26056-6-git-send-email-jiang.liu@huawei.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: On Fri, Jun 07, 2013 at 12:07:26AM +0800, Jiang Liu wrote: > 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 > Cc: stable@vger.kernel.org > --- > drivers/staging/zram/zram_drv.c | 17 ++++++++++++----- > 1 file changed, 12 insertions(+), 5 deletions(-) > > diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c > index 27ab824..9289217 100644 > --- a/drivers/staging/zram/zram_drv.c > +++ b/drivers/staging/zram/zram_drv.c > @@ -420,13 +420,20 @@ 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)) if (end >= bound || start > end) isn't enough? > return 0; > - } > > /* I/O request is valid */ > return 1; > -- > 1.8.1.2 > > -- > 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/ -- Kind regards, Minchan Kim