From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, linux-mm@kvack.org,
mm-commits@vger.kernel.org, sj@kernel.org,
stable@vger.kernel.org, torvalds@linux-foundation.org
Subject: [patch 2/2] mm/damon/dbgfs: fix 'struct pid' leaks in 'dbgfs_target_ids_write()'
Date: Thu, 30 Dec 2021 20:12:34 -0800 [thread overview]
Message-ID: <20211231041234.50dCet98O%akpm@linux-foundation.org> (raw)
In-Reply-To: <20211230201202.d9bcb24678cc3d9d503579a0@linux-foundation.org>
From: SeongJae Park <sj@kernel.org>
Subject: mm/damon/dbgfs: fix 'struct pid' leaks in 'dbgfs_target_ids_write()'
DAMON debugfs interface increases the reference counts of 'struct pid's
for targets from the 'target_ids' file write callback
('dbgfs_target_ids_write()'), but decreases the counts only in DAMON
monitoring termination callback ('dbgfs_before_terminate()').
Therefore, when 'target_ids' file is repeatedly written without DAMON
monitoring start/termination, the reference count is not decreased and
therefore memory for the 'struct pid' cannot be freed. This commit fixes
this issue by decreasing the reference counts when 'target_ids' is
written.
Link: https://lkml.kernel.org/r/20211229124029.23348-1-sj@kernel.org
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+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/damon/dbgfs.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/mm/damon/dbgfs.c~mm-damon-dbgfs-fix-struct-pid-leaks-in-dbgfs_target_ids_write
+++ a/mm/damon/dbgfs.c
@@ -353,6 +353,7 @@ static ssize_t dbgfs_target_ids_write(st
const char __user *buf, size_t count, loff_t *ppos)
{
struct damon_ctx *ctx = file->private_data;
+ struct damon_target *t, *next_t;
bool id_is_pid = true;
char *kbuf, *nrs;
unsigned long *targets;
@@ -397,8 +398,12 @@ static ssize_t dbgfs_target_ids_write(st
goto unlock_out;
}
- /* remove targets with previously-set primitive */
- damon_set_targets(ctx, NULL, 0);
+ /* remove previously set targets */
+ damon_for_each_target_safe(t, next_t, ctx) {
+ if (targetid_is_pid(ctx))
+ put_pid((struct pid *)t->id);
+ damon_destroy_target(t);
+ }
/* Configure the context for the address space type */
if (id_is_pid)
_
prev parent reply other threads:[~2021-12-31 4:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-31 4:12 incoming Andrew Morton
2021-12-31 4:12 ` [patch 1/2] userfaultfd/selftests: fix hugetlb area allocations Andrew Morton
2021-12-31 4:12 ` Andrew Morton [this message]
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