Hi Greg

I would like to as you to drop this patch (drop it also from from 6.6, 6.11 and others, if you already apllied it there).

Google engineeres said that they do not want to change the default behavior.

Mikulas

On Wed, 2 Oct 2024, gregkh@linuxfoundation.org wrote:

The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x e6a3531dd542cb127c8de32ab1e54a48ae19962b # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024100247-friction-answering-6c42@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

e6a3531dd542 ("dm-verity: restart or panic on an I/O error")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

...

From e6a3531dd542cb127c8de32ab1e54a48ae19962b Mon Sep 17 00:00:00 2001

From: Mikulas Patocka mpatocka@redhat.com Date: Tue, 24 Sep 2024 15:18:29 +0200 Subject: [PATCH] dm-verity: restart or panic on an I/O error

Maxim Suhanov reported that dm-verity doesn't crash if an I/O error happens. In theory, this could be used to subvert security, because an attacker can create sectors that return error with the Write Uncorrectable command. Some programs may misbehave if they have to deal with EIO.

This commit fixes dm-verity, so that if "panic_on_corruption" or "restart_on_corruption" was specified and an I/O error happens, the machine will panic or restart.

This commit also changes kernel_restart to emergency_restart - kernel_restart calls reboot notifiers and these reboot notifiers may wait for the bio that failed. emergency_restart doesn't call the notifiers.

Reported-by: Maxim Suhanov dfirblog@gmail.com Signed-off-by: Mikulas Patocka mpatocka@redhat.com Cc: stable@vger.kernel.org

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c index cf659c8feb29..a95c1b9cc5b5 100644 --- a/drivers/md/dm-verity-target.c +++ b/drivers/md/dm-verity-target.c @@ -272,8 +272,10 @@ static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, if (v->mode == DM_VERITY_MODE_LOGGING) return 0;

• if (v->mode == DM_VERITY_MODE_RESTART)

• kernel_restart("dm-verity device corrupted");
  

• if (v->mode == DM_VERITY_MODE_RESTART) {

• pr_emerg("dm-verity device corrupted\n");
  

• emergency_restart();
  

• }

if (v->mode == DM_VERITY_MODE_PANIC) panic("dm-verity device corrupted"); @@ -596,6 +598,23 @@ static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh) verity_fec_finish_io(io);

• if (unlikely(status != BLK_STS_OK) &&

•    unlikely(!(bio->bi_opf & REQ_RAHEAD)) &&
  

•    !verity_is_system_shutting_down()) {
  

• if (v->mode == DM_VERITY_MODE_RESTART ||
  

•     v->mode == DM_VERITY_MODE_PANIC)
  

• 	DMERR_LIMIT("%s has error: %s", v->data_dev->name,
  

• 			blk_status_to_str(status));
  

• if (v->mode == DM_VERITY_MODE_RESTART) {
  

• 	pr_emerg("dm-verity device corrupted\n");
  

• 	emergency_restart();
  

• }
  

• if (v->mode == DM_VERITY_MODE_PANIC)
  

• 	panic("dm-verity device corrupted");
  

• }
• bio_endio(bio);

}