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([2001:288:7001:2703:e6df:5ab5:fc4f:a680]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21f07afc5c1sm34494785ad.170.2025.02.05.11.06.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Feb 2025 11:06:15 -0800 (PST) From: I Hsin Cheng To: mark.rutland@arm.com Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, jserv@ccns.ncku.edu.tw, shuah@kernel.org, I Hsin Cheng Subject: [RFC PATCH] perf/core: Prevent dereferencing NULL pointer Date: Thu, 6 Feb 2025 03:06:08 +0800 Message-ID: <20250205190608.93508-1-richard120310@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit According to coverity scan check, there's possible cases where "ring_buffer_get()" returns a NULL in "perf_mmap_close". Use a "BUG_ON()" to check for NULL pointer existence, panic if it does exist, otherwise it's safe to dereference "rb" and access its members. The scan check report link is: scan5.scan.coverity.com/#/project-view/63416/10063?selectedIssue=1636067 Signed-off-by: I Hsin Cheng --- kernel/events/core.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index bcb09e011e9e..fe83d4754746 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6410,11 +6410,17 @@ static void perf_mmap_close(struct vm_area_struct *vma) { struct perf_event *event = vma->vm_file->private_data; struct perf_buffer *rb = ring_buffer_get(event); - struct user_struct *mmap_user = rb->mmap_user; - int mmap_locked = rb->mmap_locked; - unsigned long size = perf_data_size(rb); + struct user_struct *mmap_user; + int mmap_locked; + unsigned long size; bool detach_rest = false; + BUG_ON(!rb); + + mmap_user = rb->mmap_user; + mmap_locked = rb->mmap_locked; + size = perf_data_size(rb); + if (event->pmu->event_unmapped) event->pmu->event_unmapped(event, vma->vm_mm); -- 2.43.0