This is a note to let you know that I've just added the patch titled
dm crypt: avoid accessing uninitialized tasklet
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-crypt-avoid-accessing-uninitialized-tasklet.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d9a02e016aaf5a57fb44e9a5e6da8ccd3b9e2e70 Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@xxxxxxxxxx>
Date: Wed, 8 Mar 2023 14:39:54 -0500
Subject: dm crypt: avoid accessing uninitialized tasklet
From: Mike Snitzer <snitzer@xxxxxxxxxx>
commit d9a02e016aaf5a57fb44e9a5e6da8ccd3b9e2e70 upstream.
When neither "no_read_workqueue" nor "no_write_workqueue" are enabled,
tasklet_trylock() in crypt_dec_pending() may still return false due to
an uninitialized state, and dm-crypt will unnecessarily do io completion
in io_queue workqueue instead of current context.
Fix this by adding an 'in_tasklet' flag to dm_crypt_io struct and
initialize it to false in crypt_io_init(). Set this flag to true in
kcryptd_queue_crypt() before calling tasklet_schedule(). If set
crypt_dec_pending() will punt io completion to a workqueue.
This also nicely avoids the tasklet_trylock/unlock hack when tasklets
aren't in use.
Fixes: 8e14f610159d ("dm crypt: do not call bio_endio() from the dm-crypt tasklet")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Hou Tao <houtao1@xxxxxxxxxx>
Suggested-by: Ignat Korchagin <ignat@xxxxxxxxxxxxxx>
Reviewed-by: Ignat Korchagin <ignat@xxxxxxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/dm-crypt.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -68,7 +68,9 @@ struct dm_crypt_io {
struct crypt_config *cc;
struct bio *base_bio;
u8 *integrity_metadata;
- bool integrity_metadata_from_pool;
+ bool integrity_metadata_from_pool:1;
+ bool in_tasklet:1;
+
struct work_struct work;
struct tasklet_struct tasklet;
@@ -1723,6 +1725,7 @@ static void crypt_io_init(struct dm_cryp
io->ctx.r.req = NULL;
io->integrity_metadata = NULL;
io->integrity_metadata_from_pool = false;
+ io->in_tasklet = false;
atomic_set(&io->io_pending, 0);
}
@@ -1768,14 +1771,13 @@ static void crypt_dec_pending(struct dm_
* our tasklet. In this case we need to delay bio_endio()
* execution to after the tasklet is done and dequeued.
*/
- if (tasklet_trylock(&io->tasklet)) {
- tasklet_unlock(&io->tasklet);
- bio_endio(base_bio);
+ if (io->in_tasklet) {
+ INIT_WORK(&io->work, kcryptd_io_bio_endio);
+ queue_work(cc->io_queue, &io->work);
return;
}
- INIT_WORK(&io->work, kcryptd_io_bio_endio);
- queue_work(cc->io_queue, &io->work);
+ bio_endio(base_bio);
}
/*
@@ -2229,6 +2231,7 @@ static void kcryptd_queue_crypt(struct d
* it is being executed with irqs disabled.
*/
if (in_hardirq() || irqs_disabled()) {
+ io->in_tasklet = true;
tasklet_init(&io->tasklet, kcryptd_crypt_tasklet, (unsigned long)&io->work);
tasklet_schedule(&io->tasklet);
return;
Patches currently in stable-queue which might be from snitzer@xxxxxxxxxx are
queue-5.15/dm-crypt-add-cond_resched-to-dmcrypt_write.patch
queue-5.15/dm-thin-fix-deadlock-when-swapping-to-thin-device.patch
queue-5.15/dm-stats-check-for-and-propagate-alloc_percpu-failure.patch
queue-5.15/dm-crypt-avoid-accessing-uninitialized-tasklet.patch
