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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id x19sm6346863pfa.104.2021.07.31.09.07.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 31 Jul 2021 09:07:18 -0700 (PDT) Date: Sat, 31 Jul 2021 09:07:17 -0700 From: Kees Cook To: Ariel Elior , GR-everest-linux-l2@marvell.com Cc: "Gustavo A. R. Silva" , Keith Packard , Greg Kroah-Hartman , Andrew Morton , linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev, linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com, linux-hardening@vger.kernel.org Subject: Re: [PATCH 42/64] net: qede: Use memset_after() for counters Message-ID: <202107310901.CB470B8C9D@keescook> References: <20210727205855.411487-1-keescook@chromium.org> <20210727205855.411487-43-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210727205855.411487-43-keescook@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 27, 2021 at 01:58:33PM -0700, Kees Cook wrote: > In preparation for FORTIFY_SOURCE performing compile-time and run-time > field bounds checking for memset(), avoid intentionally writing across > neighboring fields. > > Use memset_after() so memset() doesn't get confused about writing > beyond the destination member that is intended to be the starting point > of zeroing through the end of the struct. > > Signed-off-by: Kees Cook > --- > The old code seems to be doing the wrong thing: starting from not the > first member, but sized for the whole struct. Which is correct? Quick ping on this question. The old code seems to be doing the wrong thing: it starts from the second member and writes beyond int_info, clobbering qede_lock: struct qede_dev { ... struct qed_int_info int_info; /* Smaller private variant of the RTNL lock */ struct mutex qede_lock; ... struct qed_int_info { struct msix_entry *msix; u8 msix_cnt; /* This should be updated by the protocol driver */ u8 used_cnt; }; Should this also clear the "msix" member, or should this not write beyond int_info? This patch does the latter. -Kees > --- > drivers/net/ethernet/qlogic/qede/qede_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/qlogic/qede/qede_main.c b/drivers/net/ethernet/qlogic/qede/qede_main.c > index 01ac1e93d27a..309dfe8c94fb 100644 > --- a/drivers/net/ethernet/qlogic/qede/qede_main.c > +++ b/drivers/net/ethernet/qlogic/qede/qede_main.c > @@ -2419,7 +2419,7 @@ static int qede_load(struct qede_dev *edev, enum qede_load_mode mode, > goto out; > err4: > qede_sync_free_irqs(edev); > - memset(&edev->int_info.msix_cnt, 0, sizeof(struct qed_int_info)); > + memset_after(&edev->int_info, 0, msix); > err3: > qede_napi_disable_remove(edev); > err2: > -- > 2.30.2 > -- Kees Cook