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zram: pass down the bvec we need to read into in the work struct

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When scheduling work item to read page we need to pass down the proper
bvec struct which points to the page to read into.  Before this patch it
uses a randomly initialized bvec (only if PAGE_SIZE != 4096) which is
wrong.

Note that without this patch on arch/kernel where PAGE_SIZE != 4096
userspace could read random memory through a zram block device (thought
userspace probably would have no control on the address being read).

Link: http://lkml.kernel.org/r/20190408183219.26377-1-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jérôme Glisse 2019-04-25 22:23:41 -07:00 committed by Linus Torvalds
parent 89c02e69fc
commit e153abc073
1 changed files with 3 additions and 2 deletions
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5
drivers/block/zram/zram_drv.c
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@ -774,18 +774,18 @@ struct zram_work {
struct zram *zram;
unsigned long entry;
struct bio *bio;
struct bio_vec bvec;
};
#if PAGE_SIZE != 4096
static void zram_sync_read(struct work_struct *work)
{
struct bio_vec bvec;
struct zram_work *zw = container_of(work, struct zram_work, work);
struct zram *zram = zw->zram;
unsigned long entry = zw->entry;
struct bio *bio = zw->bio;
read_from_bdev_async(zram, &bvec, entry, bio);
read_from_bdev_async(zram, &zw->bvec, entry, bio);
}
/*
@ -798,6 +798,7 @@ static int read_from_bdev_sync(struct zram *zram, struct bio_vec *bvec,
{
struct zram_work work;
work.bvec = *bvec;
work.zram = zram;
work.entry = entry;
work.bio = bio;