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Mon, 16 Jun 2025 19:05:55 -0700 (PDT) Received: from EBJ9932692.tcent.cn ([103.88.46.15]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-313c1b4993fsm9421536a91.30.2025.06.16.19.05.50 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 16 Jun 2025 19:05:55 -0700 (PDT) From: Lance Yang X-Google-Original-From: Lance Yang To: akpm@linux-foundation.org Cc: 21cnbao@gmail.com, david@redhat.com, Liam.Howlett@oracle.com, vbabka@suse.cz, jannh@google.com, lorenzo.stoakes@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Lance Yang Subject: [PATCH 1/1] mm/madvise: initialize prev pointer in madvise_walk_vmas Date: Tue, 17 Jun 2025 10:05:43 +0800 Message-ID: <20250617020544.57305-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 46316C000D X-Stat-Signature: oynsocxfz4fjcyn7j7a49ue9bx77gqa5 X-Rspam-User: X-HE-Tag: 1750125957-905307 X-HE-Meta: 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 xEI0Vnjq aNUYfjh8VYlxCnFPKAAQN9wCKSAf6ttkqfwOI1xtxhHlHzJYRqIK5qrGBSB8mC2b70PoBgd7OPnYFL/BK2GoE8Xsb7SubFo8Z0Sd2rGbzFaO29ku0epB9kSdIRMH4wkdSfmzofMV1V8+9/dl6o7rxP6O3IsDQM6X2qJFB0P6IRZmZTF7f3if+NSr9/yUI8QMtd+hocveXws4OEpoKisVelG0jvR18HN4WTXwsYfxH17ptt+gcN7HdKMJg9ZvIilSBeVL0POkep/6Fe8fpuVPNmc01m3dAEfsd0GbVvR+r0Z0OEzz0XsYV/gzFGFYJ5RAag9rIMXlgLQ1KtL7OmF0MHicj/vfVcO/7qI7XtD2cJIuFZvg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Lance Yang The prev pointer was uninitialized, which could lead to undefined behavior where its address is taken and passed to the visit() callback without being assigned a value. Initializing it to NULL makes the code safer and prevents potential bugs if a future callback function attempts to read from it. Signed-off-by: Lance Yang --- mm/madvise.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/madvise.c b/mm/madvise.c index 267d8e4adf31..c87325000303 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1536,10 +1536,10 @@ int madvise_walk_vmas(struct mm_struct *mm, unsigned long start, struct vm_area_struct **prev, unsigned long start, unsigned long end, void *arg)) { + struct vm_area_struct *prev = NULL; struct vm_area_struct *vma; - struct vm_area_struct *prev; - unsigned long tmp; int unmapped_error = 0; + unsigned long tmp; int error; /* -- 2.49.0