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| author | Ignat Korchagin <ignat@cloudflare.com> | 2021-01-09 16:17:06 +0100 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2021-01-12 19:51:17 +0100 |
| commit | 8e14f610159d524cd7aac37982826d3ef75c09e8 (patch) | |
| tree | 094b5c8c739481d8314bd78d4575050cf12d5e64 /drivers | |
| parent | dm integrity: fix flush with external metadata device (diff) | |
| download | linux-8e14f610159d524cd7aac37982826d3ef75c09e8.tar.xz linux-8e14f610159d524cd7aac37982826d3ef75c09e8.zip | |
dm crypt: do not call bio_endio() from the dm-crypt tasklet
Sometimes, when dm-crypt executes decryption in a tasklet, we may get
"BUG: KASAN: use-after-free in tasklet_action_common.constprop..."
with a kasan-enabled kernel.
When the decryption fully completes in the tasklet, dm-crypt will call
bio_endio(), which in turn will call clone_endio() from dm.c core code. That
function frees the resources associated with the bio, including per bio private
structures. For dm-crypt it will free the current struct dm_crypt_io, which
contains our tasklet object, causing use-after-free, when the tasklet is being
dequeued by the kernel.
To avoid this, do not call bio_endio() from the current tasklet context, but
delay its execution to the dm-crypt IO workqueue.
Fixes: 39d42fa96ba1 ("dm crypt: add flags to optionally bypass kcryptd workqueues")
Cc: <stable@vger.kernel.org> # v5.9+
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/md/dm-crypt.c | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index d2d6d3000f5b..b4d7418b5036 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -1730,6 +1730,12 @@ static void crypt_inc_pending(struct dm_crypt_io *io) atomic_inc(&io->io_pending); } +static void kcryptd_io_bio_endio(struct work_struct *work) +{ + struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work); + bio_endio(io->base_bio); +} + /* * One of the bios was finished. Check for completion of * the whole request and correctly clean up the buffer. @@ -1752,7 +1758,23 @@ static void crypt_dec_pending(struct dm_crypt_io *io) kfree(io->integrity_metadata); base_bio->bi_status = error; - bio_endio(base_bio); + + /* + * If we are running this function from our tasklet, + * we can't call bio_endio() here, because it will call + * clone_endio() from dm.c, which in turn will + * free the current struct dm_crypt_io structure with + * 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); + return; + } + + INIT_WORK(&io->work, kcryptd_io_bio_endio); + queue_work(cc->io_queue, &io->work); } /* |