From nobody Thu Apr 2 15:35:57 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5E6C629ACDD; Sat, 28 Mar 2026 00:54:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774659256; cv=none; b=k+X/TaKc02mSGyLscgme58SHOCxIXH2KjM8cZGRQvkFH9BHVcjPuFu856QY5LfpTdMNy4SF9Z3WONRRoaNNKIxFWqz3tqjmAj7kvHGKaKvjbgT8V50fKg5FkhR2mrX0HNg7J1Dej8yv5hXwEWlA/dad5swqTOQ2qsae2RhJZH1g= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774659256; c=relaxed/simple; bh=EHLWGxW7vsnb0JYbS1TWbmzJf4dzLg0vok6TKbBxOAM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HRO68WVIA4wLyp8wOUEVElXoTtr9p4V4EtIlcuODnBoFHC1F3gL+nFNoVaKljpgC3R1DyKdI7qRgPQBqDxaNyMVJZjfGv1juZWUb3+pJPBObgFPxUUn75gK4fPhv3XqHSSp3lwKUcpnGrx3m8TXCxZRdngNpfw1Sr7hjkg0kSro= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dkaZ9zBo; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dkaZ9zBo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A8D3FC2BCB0; Sat, 28 Mar 2026 00:54:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774659255; bh=EHLWGxW7vsnb0JYbS1TWbmzJf4dzLg0vok6TKbBxOAM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dkaZ9zBomPRQ+/8phFDN9AKHVfEBRRt38uDsGp6mpXJLvug7ixW8IHmvJV5eH7E3g 2oZ8SFqR90FU/B/+wzOwZEpVc1XeAgZhl4aIck42TExPvnhIg0PNSqso7vcTOy9GTt tckowld3wpqfT2RDJ+cauwTSLTnH88lQLgs795gXOMPKK0O4HVcFC2Bn5N1vbJiAjZ hfY8Qk/tqC8t0p0WWTHx2D0qFFdgAvaheMxRrML0p2nYc+r10ATRWBP6eXD2Kd25A6 SblwxnXqNOAfw8AUAQ74l8lXXctaZdUUtAaDDHzgR7VFQxxizVakS0CRU+fb61qXey QSaTIQ4Kaueug== From: SeongJae Park To: Cc: SeongJae Park , "# 6 . 16 . x" , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH 1/2] mm/damon/core: validate damos_quota_goal->nid for node_mem_{used,free}_bp Date: Fri, 27 Mar 2026 17:54:09 -0700 Message-ID: <20260328005412.7606-2-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260328005412.7606-1-sj@kernel.org> References: <20260328005412.7606-1-sj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Users can set damos_quota_goal->nid with arbitrary value for node_mem_{used,free}_bp. But DAMON core is using those for si_meminfo_node() without the validation of the value. This can result in out of bounds memory access. The issue can actually triggered using DAMON user-space tool (damo), like below. $ sudo ./damo start --damos_action stat \ --damos_quota_goal node_mem_used_bp 50% -1 \ --damos_quota_interval 1s $ sudo dmesg [...] [ 65.565986] Unable to handle kernel NULL pointer dereference at virt= ual address 0000000000000098 Fix this issue by adding the validation of the given node. If an invalid node id is given, it returns 0% for used memory ratio, and 100% for free memory ratio. Fixes: 0e1c773b501f ("mm/damon/core: introduce damos quota goal metrics for= memory node utilization") Cc: # 6.16.x Signed-off-by: SeongJae Park --- mm/damon/core.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index ddabb93f2377..9a848d7647ef 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2217,12 +2217,24 @@ static inline u64 damos_get_some_mem_psi_total(void) #endif /* CONFIG_PSI */ =20 #ifdef CONFIG_NUMA +static bool invalid_mem_node(int nid) +{ + return nid < 0 || nid >=3D MAX_NUMNODES || !node_state(nid, N_MEMORY); +} + static __kernel_ulong_t damos_get_node_mem_bp( struct damos_quota_goal *goal) { struct sysinfo i; __kernel_ulong_t numerator; =20 + if (invalid_mem_node(goal->nid)) { + if (goal->metric =3D=3D DAMOS_QUOTA_NODE_MEM_USED_BP) + return 0; + else /* DAMOS_QUOTA_NODE_MEM_FREE_BP */ + return 10000; + } + si_meminfo_node(&i, goal->nid); if (goal->metric =3D=3D DAMOS_QUOTA_NODE_MEM_USED_BP) numerator =3D i.totalram - i.freeram; --=20 2.47.3