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NFC: hci: Split memcpy() of struct hcp_message flexible array

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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: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
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>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220924040835.3364912-1-keescook@chromium.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kees Cook 2022-09-23 21:08:35 -07:00 committed by Jakub Kicinski
parent 454b20e193
commit de4feb4e3d
1 changed files with 5 additions and 7 deletions
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12
net/nfc/hci/hcp.c
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@ -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 */