Commit 34796417 authored by SeongJae Park's avatar SeongJae Park Committed by Linus Torvalds
Browse files

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: default avatarSangwoo Bae <sangwoob@amazon.com>
Fixes: 4bc05954 ("mm/damon: implement a debugfs-based user space interface")
Signed-off-by: default avatarSeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>	[5.15.x]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 595ec197

mm/damon/dbgfs.c

+2 −0
Original line number Diff line number Diff line
@@ -650,10 +650,12 @@ static void dbgfs_before_terminate(struct damon_ctx *ctx) 
	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)