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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4778c8479b7sm12365e9.3.2025.11.12.13.37.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Nov 2025 13:37:40 -0800 (PST) Date: Wed, 12 Nov 2025 21:37:39 +0000 From: David Laight To: "Lecomte, Arnaud" Cc: Brahmajit Das , syzbot+d1b7fa1092def3628bd7@syzkaller.appspotmail.com, andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, haoluo@google.com, john.fastabend@gmail.com, jolsa@kernel.org, kpsingh@kernel.org, linux-kernel@vger.kernel.org, martin.lau@linux.dev, netdev@vger.kernel.org, sdf@fomichev.me, song@kernel.org, syzkaller-bugs@googlegroups.com, yonghong.song@linux.dev Subject: Re: [PATCH bpf-next v3] bpf: Clamp trace length in __bpf_get_stack to fix OOB write Message-ID: <20251112213739.40123684@pumpkin> In-Reply-To: References: <691231dc.a70a0220.22f260.0101.GAE@google.com> <20251111081254.25532-1-listout@listout.xyz> <20251112133546.4246533f@pumpkin> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: bpf@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 Wed, 12 Nov 2025 16:11:41 +0000 "Lecomte, Arnaud" wrote: > On 12/11/2025 14:47, Brahmajit Das wrote: > > On 12.11.2025 13:35, David Laight wrote: > >> On Tue, 11 Nov 2025 13:42:54 +0530 > >> Brahmajit Das wrote: > >> > > ...snip... > >> Please can we have no unnecessary min_t(). > >> You wouldn't write: > >> x = (u32)a < (u32)b ? (u32)a : (u32)b; > >> > >> David > >> > >>> copy_len = trace_nr * elem_size; > >>> > >>> ips = trace->ip + skip; > > Hi David, > > > > Sorry, I didn't quite get that. Would prefer something like: > > trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem; > > min_t is a min with casting which is unnecessary in this case as > trace_nr and num_elem are already u32. Correct David > > > The pre-refactor code. > > >