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Tue, 01 Sep 2026 01:10:08 -0700 (PDT) Date: Tue, 1 Sep 2026 09:09:40 +0100 In-Reply-To: <20260901080941.997769-1-vdonnefort@google.com> Mime-Version: 1.0 References: <20260901080941.997769-1-vdonnefort@google.com> X-Mailer: git-send-email 2.55.0.897.gb25b4bd76c-goog Message-ID: <20260901080941.997769-18-vdonnefort@google.com> Subject: [PATCH v5 17/18] KVM: arm64: Reject hyp trace descriptors with fewer than 3 pages From: Vincent Donnefort To: maz@kernel.org, oupton@kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, kernel-team@android.com, fuad.tabba@linux.dev, qperret@google.com, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260901_011011_431897_10A01CF9 X-CRM114-Status: GOOD ( 10.37 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org A trace descriptor with 0 nr_page_va allocates a 0-size bpages backing region, which makes the ring buffer appear unloaded. Reject descriptors with nr_page_va < 3 in hyp_trace_desc_is_valid() as this is in any case the lower-limit for simple_ring_buffer. Tested-by: Fuad Tabba Reviewed-by: Fuad Tabba Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/kvm/hyp/nvhe/trace.c b/arch/arm64/kvm/hyp/nvhe/trace.c index 59349892b1e6..e34f9133e5d9 100644 --- a/arch/arm64/kvm/hyp/nvhe/trace.c +++ b/arch/arm64/kvm/hyp/nvhe/trace.c @@ -189,6 +189,10 @@ static bool hyp_trace_desc_is_valid(struct hyp_trace_desc *desc, size_t desc_siz if ((void *)rb_desc + struct_size(rb_desc, page_va, 0) > desc_end) return false; + /* simple_ring_buffer_init_mm() expects at least 3 pages */ + if (rb_desc->nr_page_va < 3) + return false; + /* Overflow desc? */ if ((void *)rb_desc + struct_size(rb_desc, page_va, rb_desc->nr_page_va) > desc_end) return false; -- 2.55.0.897.gb25b4bd76c-goog