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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id a1-20020a170902900100b0015e8d4eb2dfsm7711105plp.297.2022.05.16.20.57.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 May 2022 20:57:42 -0700 (PDT) Date: Mon, 16 May 2022 20:57:42 -0700 From: Kees Cook To: Arend van Spriel Cc: "Gustavo A . R . Silva" , linux-wireless , Linux Kernel Mailing List Subject: Re: [PATCH 05/32] brcmfmac: Use mem_to_flex_dup() with struct brcmf_fweh_queue_item Message-ID: <202205162056.F8D1BF3E@keescook> References: <20220504014440.3697851-1-keescook@chromium.org> <20220504014440.3697851-6-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Mon, May 16, 2022 at 02:49:21PM +0200, Arend van Spriel wrote: > On 5/4/2022 3:44 AM, Kees Cook wrote: > > As part of the work to perform bounds checking on all memcpy() uses, > > replace the open-coded a deserialization of bytes out of memory into a > > trailing flexible array by using a flex_array.h helper to perform the > > allocation, bounds checking, and copying. > > > Reviewed-by: Arend van Spriel Thanks! > > [...] > > diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c > > index bc3f4e4edcdf..bea798ca6466 100644 > > --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c > > +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c > > @@ -32,8 +32,8 @@ struct brcmf_fweh_queue_item { > > u8 ifidx; > > u8 ifaddr[ETH_ALEN]; > > struct brcmf_event_msg_be emsg; > > - u32 datalen; > > - u8 data[]; > > + DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(u32, datalen); > > + DECLARE_FLEX_ARRAY_ELEMENTS(u8, data); > > }; > > [...] > > @@ -414,8 +414,7 @@ void brcmf_fweh_process_event(struct brcmf_pub *drvr, > > datalen + sizeof(*event_packet) > packet_len) > > return; > > - event = kzalloc(sizeof(*event) + datalen, gfp); > > - if (!event) > > + if (mem_to_flex_dup(&event, data, datalen, gfp)) > > return; > > event->code = code; > > @@ -423,8 +422,6 @@ void brcmf_fweh_process_event(struct brcmf_pub *drvr, > > /* use memcpy to get aligned event message */ > > memcpy(&event->emsg, &event_packet->msg, sizeof(event->emsg)); > > - memcpy(event->data, data, datalen); > > - event->datalen = datalen; > > So does mem_to_flex_dup() store event->datalen? > > Don't have the entire thread so missing bits and pieces, but at least this > raises questions for me. Yes, that's part of the internal workings here -- the flex array counter is declared and will be set as part of the copy. -- Kees Cook