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b=JxkebG5+E8aGwnRfz/OniYrZag3n4/XPkJqX5Tm87e4rNVmo6wdRr90sWwcjiQVBN 9Zq4LsUbD6kBbBE0PPZbanuKErFKPRY7yaqR8fwJkwlmqcLccHiPSpvtphAAjFpHn6 h0RJYVerE0G4KsesZiqoRlgb+QTaoU2r8xHAoE/NPmKpBrkz2BVx8wzcWz1mU55FUV 5VTEewVF9LnBXMXV6cV19OI/+B3qPjyCGD3syTkbYprtTZQLOptL4ULZVFIJVG7vql lUlllxycWVippoZ+v0yTHSX689mOWA1MSTm/hT0u8RUFTFWbUNE1agPI5DQTAK9djK KJVd6fB6wp9tw== From: SJ Park To: Andrew Morton Cc: SJ Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 1/4] mm/damon/core: handle NULL ctx parameter in damon_call() Date: Wed, 2 Sep 2026 18:03:30 -0700 Message-ID: <20260903010334.93622-2-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260903010334.93622-1-sj@kernel.org> References: <20260903010334.93622-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 58A8914000B X-Stat-Signature: jycnwg5r1huixogma3fr9p61idqqo4zw X-Rspam-User: X-HE-Tag: 1788397423-460190 X-HE-Meta: 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 4G0BtdNP 57qSy6L+4Gjg/DsS3yhfA9H4sNzEQ5waqDuU7V90dM1H6Wnijfy4gWwYAR0huXLoduZaA2wfoKMaQVmk7chU9FF7YYmp2UEvRcYArN3UMtwFGJ+YDCnUutfan6m+8CM+QvyO9sChl+lkIkiLzs+YZaSxuIlVFel4+DY2DxFu3LF4kdKP/mZL6LRZQkqlwVfQKPpyp2+HgzMeiucCkIGzJEmET96A+G9CKVZmnlrChESk4sGrL1Mv3TQScaJxAOWRLEZ5rmZn73t9VyO+HvQ2MH/uyPpa5dDi+trEPIWvn148/YGs= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When NULL damon_ctx pointer parameter is passed, damon_call() could do NULL dereference. The caller is responsible to avoid that. It is easy to forget, and there are many damon_call() callers. Meanwhile, damon_call() is never meant to be performance critical. It uses mutex and completion. Add the NULL pointer check inside damon_call() so that callers can pass the parameter without NULL checks. Signed-off-by: SJ Park --- mm/damon/core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 85d29c76c00cf..03407cf7f9646 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2206,6 +2206,8 @@ int damon_kdamond_pid(struct damon_ctx *ctx) */ int damon_call(struct damon_ctx *ctx, struct damon_call_control *control) { + if (!ctx) + return -EINVAL; if (!control->repeat) init_completion(&control->completion); control->canceled = false; -- 2.47.3