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mm/damon/dbgfs: protect targets destructions with kdamond_lock

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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: 4bc05954d0 ("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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
SeongJae Park 2021-12-24 21:12:54 -08:00 committed by Linus Torvalds
parent 595ec1973c
commit 3479641796
1 changed files with 2 additions and 0 deletions
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2
mm/damon/dbgfs.c
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@ -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)