From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH] NFC: hci: Split memcpy() of struct hcp_message flexible array
Date: Fri, 23 Sep 2022 23:28:05 -0500 [thread overview]
Message-ID: <Yy6HVVMGdSCyEHbZ@work> (raw)
In-Reply-To: <20220924040835.3364912-1-keescook@chromium.org>
On Fri, Sep 23, 2022 at 09:08:35PM -0700, Kees Cook wrote:
> To work around a misbehavior of the compiler's ability to see into
> composite flexible array structs (as detailed in the coming memcpy()
> hardening series[1]), split the memcpy() of the header and the payload
> so no false positive run-time overflow warning will be generated. This
> split already existed for the "firstfrag" case, so just generalize the
> logic further.
>
> [1] https://lore.kernel.org/linux-hardening/20220901065914.1417829-2-keescook@chromium.org/
>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: netdev@vger.kernel.org
> Reported-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
> Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Thanks!
--
Gustavo
> ---
> net/nfc/hci/hcp.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/net/nfc/hci/hcp.c b/net/nfc/hci/hcp.c
> index 05c60988f59a..4902f5064098 100644
> --- a/net/nfc/hci/hcp.c
> +++ b/net/nfc/hci/hcp.c
> @@ -73,14 +73,12 @@ int nfc_hci_hcp_message_tx(struct nfc_hci_dev *hdev, u8 pipe,
> if (firstfrag) {
> firstfrag = false;
> packet->message.header = HCP_HEADER(type, instruction);
> - if (ptr) {
> - memcpy(packet->message.data, ptr,
> - data_link_len - 1);
> - ptr += data_link_len - 1;
> - }
> } else {
> - memcpy(&packet->message, ptr, data_link_len);
> - ptr += data_link_len;
> + packet->message.header = *ptr++;
> + }
> + if (ptr) {
> + memcpy(packet->message.data, ptr, data_link_len - 1);
> + ptr += data_link_len - 1;
> }
>
> /* This is the last fragment, set the cb bit */
> --
> 2.34.1
>
next prev parent reply other threads:[~2022-09-24 4:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-24 4:08 [PATCH] NFC: hci: Split memcpy() of struct hcp_message flexible array Kees Cook
2022-09-24 4:28 ` Gustavo A. R. Silva [this message]
2022-09-24 9:28 ` Krzysztof Kozlowski
2022-09-27 14:50 ` patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Yy6HVVMGdSCyEHbZ@work \
--to=gustavoars@kernel.org \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=keescook@chromium.org \
--cc=krzysztof.kozlowski@linaro.org \
--cc=kuba@kernel.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).