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Fri, 04 Jul 2025 14:28:00 -0700 (PDT) Received: from [192.168.0.56] ([38.34.87.7]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-23c8455dafcsm27271255ad.96.2025.07.04.14.27.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Jul 2025 14:28:00 -0700 (PDT) Message-ID: Subject: Re: [syzbot] [bpf?] WARNING in reg_bounds_sanity_check From: Eduard Zingerman To: Paul Chaignon Cc: syzbot , andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, 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 Date: Fri, 04 Jul 2025 14:27:58 -0700 In-Reply-To: References: <68649190.a70a0220.3b7e22.20e8.GAE@google.com> <865f2345eaa61afbd26d9de0917e3b1d887c647d.camel@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-1.fc42) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, 2025-07-04 at 14:13 -0700, Eduard Zingerman wrote: [...] > I think the mask can be computed as in or_range() function at the > bottom of the email. This gives the following algorithm, if only > unsigned range is considered: >=20 > - assume prediction is needed for "if a & b goto ..." > - bits that may be set in 'a' are or_range(a_min, a_max) > - bits that may be set in 'b' are or_range(b_min, b_max) > - if computed bit masks intersect: both branches are possible > - otherwise only false branch is possible. >=20 > Wdyt? This does not help with problem at hand, however. Possible bits set for range [0x1, 0xff] are 0xff, so there would be no prediction.