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Commit 079fa166 authored by NeilBrown's avatar NeilBrown
Browse files

md/raid1,10: Remove use-after-free bug in make_request. 

A single request to RAID1 or RAID10 might result in multiple
requests if there are known bad blocks that need to be avoided.

To detect if we need to submit another write request we test:
 	if (sectors_handled < (bio->bi_size >> 9)) {

However this is after we call **_write_done() so the 'bio' no longer
belongs to us - the writes could have completed and the bio freed.

So move the **_write_done call until after the test against
bio->bi_size.

This addresses https://bugzilla.kernel.org/show_bug.cgi?id=41862



Reported-by: default avatarBruno Wolff III <bruno@wolff.to>
Tested-by: default avatarBruno Wolff III <bruno@wolff.to>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 19d5f834

drivers/md/raid1.c

+9 −5
Original line number Diff line number Diff line
@@ -1099,12 +1099,11 @@ static int make_request(mddev_t *mddev, struct bio * bio) 
		bio_list_add(&conf->pending_bio_list, mbio);

		spin_unlock_irqrestore(&conf->device_lock, flags);

	}

	r1_bio_write_done(r1_bio);



	/* In case raid1d snuck in to freeze_array */

	wake_up(&conf->wait_barrier);



	/* Mustn't call r1_bio_write_done before this next test,

	 * as it could result in the bio being freed.

	 */

	if (sectors_handled < (bio->bi_size >> 9)) {

		r1_bio_write_done(r1_bio);

		/* We need another r1_bio.  It has already been counted

		 * in bio->bi_phys_segments

		 */
@@ -1117,6 +1116,11 @@ static int make_request(mddev_t *mddev, struct bio * bio) 
		goto retry_write;

	}



	r1_bio_write_done(r1_bio);



	/* In case raid1d snuck in to freeze_array */

	wake_up(&conf->wait_barrier);



	if (do_sync || !bitmap || !plugged)

		md_wakeup_thread(mddev->thread);

drivers/md/raid10.c

+8 −5
Original line number Diff line number Diff line
@@ -1132,13 +1132,12 @@ static int make_request(mddev_t *mddev, struct bio * bio) 
		spin_unlock_irqrestore(&conf->device_lock, flags);

	}



	/* Remove the bias on 'remaining' */

	one_write_done(r10_bio);



	/* In case raid10d snuck in to freeze_array */

	wake_up(&conf->wait_barrier);

	/* Don't remove the bias on 'remaining' (one_write_done) until

	 * after checking if we need to go around again.

	 */



	if (sectors_handled < (bio->bi_size >> 9)) {

		one_write_done(r10_bio);

		/* We need another r10_bio.  It has already been counted

		 * in bio->bi_phys_segments.

		 */
@@ -1152,6 +1151,10 @@ static int make_request(mddev_t *mddev, struct bio * bio) 
		r10_bio->state = 0;

		goto retry_write;

	}

	one_write_done(r10_bio);



	/* In case raid10d snuck in to freeze_array */

	wake_up(&conf->wait_barrier);



	if (do_sync || !mddev->bitmap || !plugged)

		md_wakeup_thread(mddev->thread);