zram: pass down the bvec we need to read into in the work struct
authorJérôme Glisse <jglisse@redhat.com>
Fri, 26 Apr 2019 05:23:41 +0000 (22:23 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 26 Apr 2019 16:18:05 +0000 (09:18 -0700)
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>
drivers/block/zram/zram_drv.c

index 399cad7daae77b37508033ec1cac61bebefbc550..d58a359a66225f39682c067739eb9843bae36b80 100644 (file)
@@ -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;