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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48899d1b12bsm20958925e9.5.2026.04.03.03.00.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Apr 2026 03:00:35 -0700 (PDT) Date: Fri, 3 Apr 2026 11:00:34 +0100 From: David Laight To: Aleksandr Loktionov Cc: intel-wired-lan@lists.osuosl.org, anthony.l.nguyen@intel.com, netdev@vger.kernel.org Subject: Re: [PATCH iwl-next] ixgbe: fix integer overflow and wrong bit position in ixgbe_validate_rtr() Message-ID: <20260403110034.6fe45f70@pumpkin> In-Reply-To: <20260327073046.134085-10-aleksandr.loktionov@intel.com> References: <20260327073046.134085-1-aleksandr.loktionov@intel.com> <20260327073046.134085-10-aleksandr.loktionov@intel.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: netdev@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, 27 Mar 2026 08:30:44 +0100 Aleksandr Loktionov wrote: > Two bugs in the same loop in ixgbe_validate_rtr(): > > 1. When extracting 3-bit traffic class values from the IXGBE_RTRUP2TC > register the shifted value was assigned directly to a u8, silently > truncating any bits above bit 7. Mask with IXGBE_RTRUP2TC_UP_MASK > before the assignment so only the intended 3 bits are kept. > > 2. When clearing an out-of-bounds entry the mask was always shifted by > the fixed constant IXGBE_RTRUP2TC_UP_SHIFT (== 3), regardless of > which loop iteration was being processed. This means only the entry > at bit position 3 was ever cleared; entries at bit positions 0, 6, 9, > ..., 21 were left unreset. Use i * IXGBE_RTRUP2TC_UP_SHIFT to target > the correct field for each iteration. > > Also replace the hardcoded 0x7 literal with the IXGBE_RTRUP2TC_UP_MASK > constant for consistency with other parts of the driver. > > Signed-off-by: Aleksandr Loktionov > --- > drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c > index 9aec66c..53b82a5 100644 > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c > @@ -9798,11 +9798,12 @@ static void ixgbe_validate_rtr(struct ixgbe_adapter *adapter, u8 tc) > rsave = reg; > > for (i = 0; i < MAX_TRAFFIC_CLASS; i++) { > - u8 up2tc = reg >> (i * IXGBE_RTRUP2TC_UP_SHIFT); > + u8 up2tc = IXGBE_RTRUP2TC_UP_MASK & > + (reg >> (i * IXGBE_RTRUP2TC_UP_SHIFT)); That really ought to be the opposite way round: expr & constant. Or add a second line to mask the value. David > > /* If up2tc is out of bounds default to zero */ > if (up2tc > tc) > - reg &= ~(0x7 << IXGBE_RTRUP2TC_UP_SHIFT); > + reg &= ~(IXGBE_RTRUP2TC_UP_MASK << (i * IXGBE_RTRUP2TC_UP_SHIFT)); > } > > if (reg != rsave)