+ mm-damon-dbgfs-protect-targets-destructions-with-kdamond_lock.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: mm/damon/dbgfs: protect targets destructions with kdamond_lock
has been added to the -mm tree.  Its filename is
     mm-damon-dbgfs-protect-targets-destructions-with-kdamond_lock.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-damon-dbgfs-protect-targets-destructions-with-kdamond_lock.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-damon-dbgfs-protect-targets-destructions-with-kdamond_lock.patch

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------------------------------------------------------
From: SeongJae Park <sj@kernel.org>
Subject: mm/damon/dbgfs: protect targets destructions with kdamond_lock

DAMON debugfs interface iterates current monitoring targets in
'dbgfs_target_ids_read()' while holding the corresponding 'kdamond_lock'. 
However, it also destructs the monitoring targets in
'dbgfs_before_terminate()' without holding the lock.  This can result in a
use_after_free bug.  This commit avoids the race by protecting the
destruction with the corresponding 'kdamond_lock'.

Link: https://lkml.kernel.org/r/20211221094447.2241-1-sj@kernel.org
Reported-by: Sangwoo Bae <sangwoob@amazon.com>
Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>	[5.15.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/damon/dbgfs.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/mm/damon/dbgfs.c~mm-damon-dbgfs-protect-targets-destructions-with-kdamond_lock
+++ a/mm/damon/dbgfs.c
@@ -650,10 +650,12 @@ static void dbgfs_before_terminate(struc
 	if (!targetid_is_pid(ctx))
 		return;
 
+	mutex_lock(&ctx->kdamond_lock);
 	damon_for_each_target_safe(t, next, ctx) {
 		put_pid((struct pid *)t->id);
 		damon_destroy_target(t);
 	}
+	mutex_unlock(&ctx->kdamond_lock);
 }
 
 static struct damon_ctx *dbgfs_new_ctx(void)
_

Patches currently in -mm which might be from sj@kernel.org are

mm-damon-dbgfs-protect-targets-destructions-with-kdamond_lock.patch
mm-damon-remove-some-no-need-func-definitions-in-damonh-file-fix.patch
mm-damon-convert-macro-functions-to-static-inline-functions.patch
docs-admin-guide-mm-damon-usage-update-for-scheme-quotas-and-watermarks.patch
docs-admin-guide-mm-damon-usage-remove-redundant-information.patch
docs-admin-guide-mm-damon-usage-mention-tracepoint-at-the-beginning.patch
docs-admin-guide-mm-damon-usage-update-for-kdamond_pid-and-mkrm_contexts.patch
mm-damon-remove-a-mistakenly-added-comment-for-a-future-feature.patch
mm-damon-schemes-account-scheme-actions-that-successfully-applied.patch
mm-damon-schemes-account-how-many-times-quota-limit-has-exceeded.patch
mm-damon-reclaim-provide-reclamation-statistics.patch
docs-admin-guide-mm-damon-reclaim-document-statistics-parameters.patch
mm-damon-dbgfs-support-all-damos-stats.patch
docs-admin-guide-mm-damon-usage-update-for-schemes-statistics.patch