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b=oP6TEdb7YE2T2S8Ap9nwc/X3asue9bKewcgHIuUVA3FoCpyOmXmfThSlzYPyAK/rP 4QmN0JpN+rFzUZGkj7ZfF+6czDfH3GIzjeosnlj8ZOiateuLnVjtxdSz4wROmB22Fe vfrhicja1vsznPCIbFme0J4tO5KEpXgaiaY+tIDY9AwqLc2dTu1wu19uR7qZEUmZ/g OEgxNsGwqMrDhnvjqnWWGtfTN0rV/BICgDQCteeZ6t/gqmEDxcGxYzVjvKStGgtfOW na16XywlEeyZIaWoOiS06QOBLiNnnO6YFDoUHguGw1tVAVRvr6V1alfU6Krbou9WWZ q88hFGa4q31RQ== Date: Sat, 26 Jul 2025 16:19:18 -0700 From: Kees Cook To: Linus Torvalds CC: Bhupesh , akpm@linux-foundation.org, kernel-dev@igalia.com, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, oliver.sang@intel.com, lkp@intel.com, laoar.shao@gmail.com, pmladek@suse.com, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, arnaldo.melo@gmail.com, alexei.starovoitov@gmail.com, andrii.nakryiko@gmail.com, mirq-linux@rere.qmqm.pl, peterz@infradead.org, willy@infradead.org, david@redhat.com, viro@zeniv.linux.org.uk, ebiederm@xmission.com, brauner@kernel.org, jack@suse.cz, mingo@redhat.com, juri.lelli@redhat.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-trace-kernel@vger.kernel.org Subject: =?US-ASCII?Q?Re=3A_=5BPATCH_v6_2/3=5D_treewide=3A_Switch_memcpy=28=29_use?= =?US-ASCII?Q?rs_of_=27task-=3Ecomm=27_to_a_more_safer_implementation?= User-Agent: K-9 Mail for Android In-Reply-To: References: <20250724123612.206110-1-bhupesh@igalia.com> <20250724123612.206110-3-bhupesh@igalia.com> <202507241640.572BF86C70@keescook> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Stat-Signature: nb89uafamo3gu65mnhfgsoe891sihbju X-Rspamd-Queue-Id: A6FDD40005 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1753571961-756562 X-HE-Meta: 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 HvdbGqPt XvWsc3esxZmB0u7biHk4DAHRN6ndkW9H4UYhlvBKpH2Qa6R0UETVMfW+kn9c9K+Z7pIXRmLeY41ZTxJPHE0pZudANKG9/CdUMSzJCVR+CfeA8hb6y2CDYMl54aDYxLE4xtXLbfyEcYOxyb497itupCOOlsc2qEqo3JKBAljA0rEcOfsgdj4AIfzoTc+CnXwGAzxhw9dxFHUa+zEG1revllJdBvFO7iqx5O7Ks3SgnWmHUQcQMvDJ/Br88GmJ57JGUFzerZwFhwbQLPMHYL1qXiKqVBMK9boEq6GQEFHnUOUQyia2xmImmiMg5cEbzKIB6eQGVLgkeqwu3lc02l9davlsf34IJ27fBKLUAszXf1fISrDV+4YlcFNUllLo0nLRIXlJmDp+uvAkk4jdB/k+dGoLfF7rO4IE83++jv3Urb421hVeEq3tOtEddAA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On July 26, 2025 10:50:55 AM PDT, Linus Torvalds wrote: >, but > >On Thu, 24 Jul 2025 at 16:49, Kees Cook wrote: >> >> Why not switch all of these to get_task_comm()? It will correctly handl= e >> the size check and NUL termination=2E > >I'd rather aim to get rid of get_task_comm() entirely=2E That works for me! I just get twitchy around seeing memcpy used for string= s=2E :) if we're gonna NUL after the memcpy, just use strscpy_pad()=2E >And guess what? We *have* that function=2E It's called "strscpy()"=2E It >already does the right thing, including passing in the size of a fixed >array and just dealing with it the RightWay(tm)=2E Add '_pad()' if that >is the behavior you want, and now you *document* the fact that the >result is padded=2E Exactly=2E Let's see how much we can just replace with strscpy_pad()=2E It= we have other use cases, we can handle those separately=2E -Kees --=20 Kees Cook