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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> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: yikpnqqxpknz57r8suqkw3qqg546sgoo X-Rspamd-Queue-Id: A5471C0007 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1774659256-968091 X-HE-Meta: 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 IHIiMn8i L2sjeT4JLI1fuqqef6eAPSTJQy2y5PehLLfobRxPodXChrVEYlwJ/QcLDpkL7Lz1uJPUJS9fFLfmMnqBTarvW4j0B8LXYBwXeupPlqZ5igOQRleFtwjkTrXkCQsLG5GUlJAJs6ZVg9sIKbNW4PsmCMAyJ11UIc7E1gkQK8jdJI3nlRFSlrrF2lKMsKHiP25ju1rhzaBTleRun64XtNwUoHQJwsNwuZcso1s7DNOAJH8ORc3Kciw5Sn/R+w22cYrujm8NKN4Sc5ZRZpOAZHf9d3vTMoA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 virtual 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 */ #ifdef CONFIG_NUMA +static bool invalid_mem_node(int nid) +{ + return nid < 0 || nid >= 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; + if (invalid_mem_node(goal->nid)) { + if (goal->metric == 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 == DAMOS_QUOTA_NODE_MEM_USED_BP) numerator = i.totalram - i.freeram; -- 2.47.3