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([2a10:d582:31e:0:901:1329:d82a:8818]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42f7d222478sm9481624f8f.20.2025.12.05.08.36.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 Dec 2025 08:36:32 -0800 (PST) Message-ID: Date: Fri, 5 Dec 2025 16:36:31 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] hw/dma/omap_dma.c: Use 64 bit maths for omap_dma_transfer_setup To: Peter Maydell Cc: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , =?UTF-8?Q?Alex_Benn=C3=A9e?= , qemu-devel@nongnu.org References: <20251204193311.1281133-1-jim.macarthur@linaro.org> <87qztarkyf.fsf@draig.linaro.org> <364a1c91-c7a0-41b1-8ae9-902b3158914c@linaro.org> Content-Language: en-US From: Jim MacArthur In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::436; envelope-from=jim.macarthur@linaro.org; helo=mail-wr1-x436.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 On 12/5/25 16:20, Peter Maydell wrote: > On Fri, 5 Dec 2025 at 16:11, Jim MacArthur wrote: >> >> On 12/5/25 15:57, Philippe Mathieu-Daudé wrote: >>> On 4/12/25 22:33, Alex Bennée wrote: >>>> Jim MacArthur writes: >>>> >>>>> If both frame and element count are 65535, which appears valid from my >>>>> reading of the OMAP5912 documentation, then some of the calculations >>>>> will overflow the 32-bit signed integer range and produce a negative >>>>> min_elems value. >>>>> >>>>> Raised by #3204 (https://gitlab.com/qemu-project/qemu/-/issues/3204). >>>>> >>>> nit: >>>> >>>> Fixes: https://gitlab.com/qemu-project/qemu/-/issues/3204 >>> Format is: >>> >>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3204 >>> Fixes: afbb5194d43 ("Handle on-chip DMA controllers in one place") >>> >> I'm unclear on whether this actually resolves or fixes the issue, so I >> just said 'Raised by'. The bug only includes a test case, not a text >> description of the problem. The test case will give a different error if >> this patch is applied, but still doesn't pass. I've mentioned this on >> the bug page. > Generally for this kind of fuzzer-generated bug report, the > bug is "it is possible to make QEMU assert/crash/etc". They > don't come with textual analysis of why exactly we ended up > crashing, because the crash was auto-generated. So the > "what actually happened here" is one of the things you have > to figure out as part of fixing the bug. By that criterion, this patch doesn't fix the bug as it will still throw a different address sanitizer error. The test case identified at least two problems, one of which is fixed by this patch (when I address your comments about u64/u32 math) and the other which I haven't figured out how to address yet. I can leave this without the Resolves: tag, or add an extra issue to Gitlab with the specific problem, or we can leave it until we have a patch for the other problems. Jim