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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42f7d331aeasm9768523f8f.37.2025.12.05.10.28.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Dec 2025 10:28:18 -0800 (PST) Date: Fri, 5 Dec 2025 18:28:13 +0000 From: David Laight To: Ard Biesheuvel Cc: Tvrtko Ursulin , Ard Biesheuvel , linux-kernel@vger.kernel.org, Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Simona Vetter , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH] drm/i195: Fix format string truncation warning Message-ID: <20251205182813.09231c45@pumpkin> In-Reply-To: References: <20251107164240.2023366-2-ardb+git@google.com> <14ca1b28-df1d-4065-ad7a-97a3ff81a5a4@ursulin.net> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 5 Dec 2025 11:48:08 +0100 Ard Biesheuvel wrote: > On Sun, 9 Nov 2025 at 19:00, Ard Biesheuvel wrote: ... > > > But I guess much prettier fix would be to simply grow the buffer. > > > > > > > OK, so something like > > --- a/drivers/gpu/drm/i915/intel_memory_region.h > +++ b/drivers/gpu/drm/i915/intel_memory_region.h > @@ -72,7 +72,7 @@ struct intel_memory_region { > u16 instance; > enum intel_region_id id; > char name[16]; > - char uabi_name[16]; > + char uabi_name[20]; The observant will notice the 7 bytes of padding following 'private', and another 7 a little later on. (I' pretty sure 'bool' is u8). So extending the buffer doesn't even grow the structure. The string is only used when printing some stats. I got lost in a list of #defines and function pointers trying to find the actual function that did the 'printf'. David > bool private; /* not for userspace */ > > struct { > > > > > > Also, hm, how come gcc does not find the mem->name vsnprintf from > > > intel_memory_region_set_name? > > > > > > > AFAICT, intel_memory_region_set_name() is never called with a format > string that could produce more than 15/16 bytes of output. >