From: Josh Law <objecting@objecting.org>
To: sj@kernel.org, akpm@linux-foundation.org
Cc: damon@lists.linux.dev, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Josh Law <objecting@objecting.org>
Subject: [PATCH 3/4] mm/damon/sysfs: check contexts->nr in update_schemes_tried_regions
Date: Thu, 19 Mar 2026 15:57:41 +0000 [thread overview]
Message-ID: <20260319155742.186627-4-objecting@objecting.org> (raw)
In-Reply-To: <20260319155742.186627-1-objecting@objecting.org>
damon_sysfs_update_schemes_tried_regions() and its callback
damon_sysfs_schemes_tried_regions_upd_one() access contexts_arr[0]
without verifying nr_contexts >= 1. This can NULL deref if damon_ctx is
non-NULL (preserved after stop) but nr_contexts has been set to 0. Add
the missing check.
Signed-off-by: Josh Law <objecting@objecting.org>
---
mm/damon/sysfs.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 36ad2e8956c9..ddcdc4e35b27 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1731,6 +1731,8 @@ static int damon_sysfs_update_schemes_tried_regions(
if (!ctx)
return -EINVAL;
+ if (sysfs_kdamond->contexts->nr != 1)
+ return -EINVAL;
damon_sysfs_schemes_clear_regions(
sysfs_kdamond->contexts->contexts_arr[0]->schemes);
--
2.34.1
next prev parent reply other threads:[~2026-03-19 15:58 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-19 15:57 [PATCH 0/4] mm/damon/sysfs: fix resource leak and NULL pointer dereferences Josh Law
2026-03-19 15:57 ` [PATCH 1/4] mm/damon/sysfs: fix param_ctx leak on damon_sysfs_new_test_ctx() failure Josh Law
2026-03-20 2:00 ` SeongJae Park
2026-03-19 15:57 ` [PATCH 2/4] mm/damon/sysfs: check contexts->nr before clear_schemes_tried_regions Josh Law
2026-03-20 2:13 ` SeongJae Park
2026-03-20 7:06 ` Josh Law
2026-03-20 14:47 ` SeongJae Park
2026-03-20 15:14 ` Josh Law
2026-03-20 15:51 ` SeongJae Park
2026-03-20 15:56 ` Josh Law
2026-03-19 15:57 ` Josh Law [this message]
2026-03-20 2:15 ` [PATCH 3/4] mm/damon/sysfs: check contexts->nr in update_schemes_tried_regions SeongJae Park
2026-03-19 15:57 ` [PATCH 4/4] mm/damon/sysfs: check contexts->nr in repeat_call_fn Josh Law
2026-03-20 2:06 ` SeongJae Park
2026-03-19 19:24 ` [PATCH 0/4] mm/damon/sysfs: fix resource leak and NULL pointer dereferences Josh Law
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260319155742.186627-4-objecting@objecting.org \
--to=objecting@objecting.org \
--cc=akpm@linux-foundation.org \
--cc=damon@lists.linux.dev \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=sj@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox