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b=AnLPvUs2bfRc5Fet8oP+MqRgbZWzlG7vgETZO9x+3SuSwDE+iesC91KdrglmxTEt7 WtRfBJzd3S7U7EICJWfY2f1zdkUJB/J29h5CiJZeyqa31EjL/hW11IUAcyVycLIDs/ L6Ew5nCO/PVTQCkKAYCJnTb0rop5KgUIpet5xGfTk/meIRaBG8gJKzETKAUkM/1mLW neIFy1ETOHaqUEF/1hOUg7mRa/pC+eN79T8r34lj8fqHu88nUTjKMwCA7Z70XURdz0 ZUy6h81b6gzb8fEu7af7ugkCiJglRmlR6GjkBRq+ih4YJxSf4dkOUlG+D+l/zGlrJW t7NY7+W6HHb1A== Date: Sun, 30 Nov 2025 11:38:36 +0200 From: Mike Rapoport To: Pasha Tatashin Cc: pratyush@kernel.org, dmatlack@google.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] liveupdate: luo_core: fix redundant bound check in luo_ioctl() Message-ID: References: <20251130010919.1488230-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251130010919.1488230-1-pasha.tatashin@soleen.com> X-Rspamd-Queue-Id: 3F6F81A000C X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: yn8r93xtnpbq7c8to14ftfqfcq3cj53p X-HE-Tag: 1764495523-61183 X-HE-Meta: U2FsdGVkX1/Qmir3lUCOwcHDhg2xbLtl8KsAtGz7H4R+w4zMzQNwnELMVnNHeyDQwQ50x5029sRQ68O5S70T6Sieb/l8rGN0Oy3Km2JVmo3uxfSb4vlKks46lkCiSDyjdsUHs9kriK2E9YkrJWx1oyHVGta1j2hC7ONbIyhECb6KjgQlNk3guzpHr1ZLB7ansj9H3kz9FALPjDYwsBCu6GlsJI0EUIKFxSztggoe51ee57xw9HmJeSJYWT9fKnP7Gw092QuGUxSj4alfENh63PklIswqVL2V/QOgd495QLl0VHq2UI4eLqfcFXcYOCBWLz5vExo0hjoEd4jExPdnpC0QxDvfAZHQVqtJdSurA8Y/APMPSp0E8hTlKFaK+GIt6VG0AJy+ofcoL0XS1mpKXQmTh+7cU44Lbf5JiDKpQxF2z1x7JDheqJZqBD7vHYiqAKU3y8Xfn7t4Ps8jYOviJG6cTeKBg2Mo+MOOgSkBELY5yvhqF+lEjMSzP7KQodEZuZ44RWjT42QzH0Aqc7Y18utlak9Zd3UDOt/YDJ4dgqVDr7thGECeR0mTRuLWqbqAfiezi+6DLKzUb6So//XmhgrygNgiC9vB10HuO82Zr3xS6CFPScUilNOOtt26ZL2kQijYEPCxB0/wDe4U63nDJ/o3LAnCo8/Glo3LG8Y6eERL0CX9J9Nr1/fOabIzZInJu2a6BtA8c+mArPIkmQkqId6iyCHCh4Wr/xoE4G9d7H0W/cN4FQJporHK5oL82cwATAKP5EiZcflKG75vZGUPm7f7R7bxGtJYW7cNAUVgvfVWG0jCTNtQ9VSnrItYFbI0v4DQ6Z0DU/rYcu5lokkPDicM7WQlR/OKtN9/+GMyxKQyz76R/vBnNKhZwmkkF55LSi7sGu1imLMv2ygG0nH48rZlGcUp/0kqJfQySa4gSG3V1cO1y7b4bPzxco3b2dJZX46FIO+pTTLv+1Y20Qg ol0Sq2nh +kCnJ0l3Ot0i63YIcuFkoVh5q5iz8Gziyi3+qrTDJdM3PVvBKg0hu6RQUEIhlN0AcDhmoZYAyxQ64F4+hecmymYkKkpcHp6RKe/fjnX8qGeSCixmqp7gD7dewB2+p8cLWp6FeiO+8sDRzNVLLlASI6v5FqcTJgVa/R7sCteVfCEneerbAyUXXj06fe1sw1qVI8dqtCGYCu7GpBAg9vLt+4tcIbTEoXlM+tc20WPJnH5GnkoTtLVzwl+vhhqfY1OuU7P9jCSvRgGvJ3YhWNqqLjJhv2gmSCnnUme0LgLkjHZrZgAM+VW8lB12SYv7FVJrOe3HJEI9OqNAhZTcLczzDeRSijLBtkjAZRwEai9rjGnXaeJHiD+nuay07WEQfsggytxzwZ8iabwd5LIHIRDYP0bU25g== 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 Sat, Nov 29, 2025 at 08:09:19PM -0500, Pasha Tatashin wrote: > The kernel test robot reported a Smatch warning: > kernel/liveupdate/luo_core.c:402 luo_ioctl() warn: unsigned 'nr' is > never less than zero. > > This occurs because 'nr' is unsigned and LIVEUPDATE_CMD_BASE is > currently defined as 0, making the check (nr < LIVEUPDATE_CMD_BASE) > always false. > > Remove the explicit lower bound check. The logic remains correct because > 'nr' is unsigned; if nr is less than LIVEUPDATE_CMD_BASE, the expression > (nr - LIVEUPDATE_CMD_BASE) will wrap around to a large positive value. > This will inevitably be larger than ARRAY_SIZE(luo_ioctl_ops) and be > caught by the upper bound check. > > Reported-by: kernel test robot > Closes: https://lore.kernel.org/oe-kbuild-all/202511280300.6pvBmXUS-lkp@intel.com/ > Signed-off-by: Pasha Tatashin Reviewed-by: Mike Rapoport (Microsoft) > --- > kernel/liveupdate/luo_core.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/kernel/liveupdate/luo_core.c b/kernel/liveupdate/luo_core.c > index 69298d82f404..7a9ef16b37d8 100644 > --- a/kernel/liveupdate/luo_core.c > +++ b/kernel/liveupdate/luo_core.c > @@ -404,10 +404,8 @@ static long luo_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) > int err; > > nr = _IOC_NR(cmd); > - if (nr < LIVEUPDATE_CMD_BASE || > - (nr - LIVEUPDATE_CMD_BASE) >= ARRAY_SIZE(luo_ioctl_ops)) { > + if (nr - LIVEUPDATE_CMD_BASE >= ARRAY_SIZE(luo_ioctl_ops)) > return -EINVAL; > - } > > ucmd.ubuffer = (void __user *)arg; > err = get_user(ucmd.user_size, (u32 __user *)ucmd.ubuffer); > > base-commit: 7d31f578f3230f3b7b33b0930b08f9afd8429817 > -- > 2.52.0.487.g5c8c507ade-goog > -- Sincerely yours, Mike.