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Thu, 03 Sep 2026 13:20:11 -0700 (PDT) Date: Thu, 3 Sep 2026 13:20:10 -0700 From: Joe Damato To: Jakub Kicinski Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, florian.fainelli@broadcom.com, jonas.gorski@gmail.com, andrew@lunn.ch, olteanv@gmail.com, vivien.didelot@gmail.com, f.fainelli@gmail.com Subject: Re: [PATCH net 4/5] net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size Message-ID: Mail-Followup-To: Joe Damato , Jakub Kicinski , davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, florian.fainelli@broadcom.com, jonas.gorski@gmail.com, andrew@lunn.ch, olteanv@gmail.com, vivien.didelot@gmail.com, f.fainelli@gmail.com References: <20260903032611.3000029-1-kuba@kernel.org> <20260903032611.3000029-5-kuba@kernel.org> 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-Disposition: inline In-Reply-To: <20260903032611.3000029-5-kuba@kernel.org> On Wed, Sep 02, 2026 at 08:26:10PM -0700, Jakub Kicinski wrote: > mv88e6xxx_get_rxnfc() uses rxnfc->rule_cnt as the write index while > dumping the policy IDR, clobbering the input value before it has been > looked at. That input is the number of entries the caller had room for. > ETHTOOL_GRXCLSRLALL requires no CAP_NET_ADMIN and the ioctl sizes the > buffer from the rule_cnt userspace passes in, so once an admin has > installed policy rules any user can ask for fewer slots than there are > rules and run off the end of the allocation. A rule_cnt of 0 leaves the > buffer pointer NULL and the walk dereferences it. > > Count into a local so the caller's limit survives the walk, and stop with > -EMSGSIZE once it is reached. > > Fixes: da7dc8755304 ("net: dsa: mv88e6xxx: add RXNFC support") > Signed-off-by: Jakub Kicinski > --- > CC: andrew@lunn.ch > CC: olteanv@gmail.com > CC: vivien.didelot@gmail.com > CC: f.fainelli@gmail.com > --- > drivers/net/dsa/mv88e6xxx/chip.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) Reviewed-by: Joe Damato