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Thu, 19 Mar 2026 16:57:45 +0100 (CET) From: Josh Law To: sj@kernel.org, akpm@linux-foundation.org Cc: damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Josh Law Subject: [PATCH 2/4] mm/damon/sysfs: check contexts->nr before clear_schemes_tried_regions Date: Thu, 19 Mar 2026 15:57:40 +0000 Message-Id: <20260319155742.186627-3-objecting@objecting.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260319155742.186627-1-objecting@objecting.org> References: <20260319155742.186627-1-objecting@objecting.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-ZohoMailClient: External X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: C8955120010 X-Stat-Signature: umq5h7ahyeoprdqcydiukfa1zzbt7ytf X-HE-Tag: 1773935880-215544 X-HE-Meta: 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 xLqk1ZBH sxAK4gYwrdXk14+hW5rhja9kIU+fsffG1v+VEXQhk3/OWsHV4FkqDx9AsIlsXZ+cA/zfHvVOKdXWcl6bsypEXU4doI8ES2ViBvjTMc0mZEQexlJVuUnI/+hdnoniom7LYsA0qdlUouc5RQN9cTPGL1Qi4egkADBI8cD0RkDg6ClPNwdh/dVGR8fdXFR5h3Ky7bZjNZ0dFhvmdGf0ODEleo6yIvOndpXjGEKbwUaOos0g9ZKMJm/Bwhphqt00uySL1JcGuWEgO50XgtEjk7ujxnAyJneS91cxCBALxDPMu1EYOVoZmfp32I8xle+Q52qYMGwujFm2i0YEeReEQs1rCFKd1FxbSN6kU6rZBspNUwetNEGFF/ZgIxWenyysKGnkHaO703zC1FrrFziQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The CLEAR_SCHEMES_TRIED_REGIONS command accesses contexts_arr[0] without verifying nr_contexts >= 1, causing a NULL pointer dereference when no context is configured. Add the missing check. Signed-off-by: Josh Law --- mm/damon/sysfs.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c index b573b9d60784..36ad2e8956c9 100644 --- a/mm/damon/sysfs.c +++ b/mm/damon/sysfs.c @@ -1769,6 +1769,8 @@ static int damon_sysfs_handle_cmd(enum damon_sysfs_cmd cmd, case DAMON_SYSFS_CMD_UPDATE_SCHEMES_TRIED_REGIONS: return damon_sysfs_update_schemes_tried_regions(kdamond, false); case DAMON_SYSFS_CMD_CLEAR_SCHEMES_TRIED_REGIONS: + if (kdamond->contexts->nr != 1) + return -EINVAL; return damon_sysfs_schemes_clear_regions( kdamond->contexts->contexts_arr[0]->schemes); case DAMON_SYSFS_CMD_UPDATE_SCHEMES_EFFECTIVE_QUOTAS: -- 2.34.1