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[2001:8b0:1d0::2]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47787e8e798sm146772835e9.10.2025.11.14.07.21.20 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Nov 2025 07:21:20 -0800 (PST) From: Peter Maydell To: qemu-devel@nongnu.org Subject: [PULL 09/10] hw/misc/npcm_clk: Don't divide by zero when calculating frequency Date: Fri, 14 Nov 2025 15:21:09 +0000 Message-ID: <20251114152110.2547285-10-peter.maydell@linaro.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251114152110.2547285-1-peter.maydell@linaro.org> References: <20251114152110.2547285-1-peter.maydell@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::32b; envelope-from=peter.maydell@linaro.org; helo=mail-wm1-x32b.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org If the guest misprograms the PLL registers to request a zero divisor, we currently fall over with a division by zero: ../../hw/misc/npcm_clk.c:221:14: runtime error: division by zero SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ../../hw/misc/npcm_clk.c:221:14 Thread 1 "qemu-system-aar" received signal SIGFPE, Arithmetic exception. 0x00005555584d8f6d in npcm7xx_clk_update_pll (opaque=0x7fffed159a20) at ../../hw/misc/npcm_clk.c:221 221 freq /= PLLCON_INDV(con) * PLLCON_OTDV1(con) * PLLCON_OTDV2(con); Avoid this by treating this invalid setting like a stopped clock (setting freq to 0). Cc: qemu-stable@nongnu.org Resolves: https://gitlab.com/qemu-project/qemu/-/issues/549 Signed-off-by: Peter Maydell Reviewed-by: Philippe Mathieu-Daudé Message-id: 20251107150137.1353532-1-peter.maydell@linaro.org --- hw/misc/npcm_clk.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/hw/misc/npcm_clk.c b/hw/misc/npcm_clk.c index c48d40b4468..e202a8a2998 100644 --- a/hw/misc/npcm_clk.c +++ b/hw/misc/npcm_clk.c @@ -212,13 +212,14 @@ static void npcm7xx_clk_update_pll(void *opaque) { NPCM7xxClockPLLState *s = opaque; uint32_t con = s->clk->regs[s->reg]; - uint64_t freq; + uint64_t freq, freq_div; /* The PLL is grounded if it is not locked yet. */ if (con & PLLCON_LOKI) { freq = clock_get_hz(s->clock_in); freq *= PLLCON_FBDV(con); - freq /= PLLCON_INDV(con) * PLLCON_OTDV1(con) * PLLCON_OTDV2(con); + freq_div = PLLCON_INDV(con) * PLLCON_OTDV1(con) * PLLCON_OTDV2(con); + freq = freq_div ? freq / freq_div : 0; } else { freq = 0; } -- 2.43.0