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a=openpgp; fpr=87A9BD933F87C606D276F62DDAE8E10975969CE5 X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=marcandre.lureau@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 4 X-Spam_score: 0.4 X-Spam_bar: / X-Spam_report: (0.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.852, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1785930837619158500 A guest can send bulk-out commands faster than the card backend produces responses. Each XfrBlock adds a pending answer slot, and other commands immediately allocate a bulk_in_pending entry. Once all BULK_IN_PENDING_NUM slots are full, ccid_reserve_recv_buf() returns NULL and responses are silently dropped. NAK the bulk-out endpoint at message boundaries when bulk_in_pending_num + pending_answers_num >=3D BULK_IN_PENDING_NUM, so the guest retries later, giving the response pipeline time to drain. Change ccid_write_data_block_answer() to peek the next answer before attempting to write the data block: if the bulk-in ring is full, the pending answer is preserved for retry rather than being consumed and lost. Update ccid_flush_pending_answers() to break on failure so it does not loop forever when the ring is full. Fixes: 367071447ec5 ("usb-ccid: add CCID bus") Signed-off-by: Marc-Andr=C3=A9 Lureau --- hw/usb/dev-smartcard-reader.c | 38 ++++++++++++++++++++++++++++++-------- 1 file changed, 30 insertions(+), 8 deletions(-) diff --git a/hw/usb/dev-smartcard-reader.c b/hw/usb/dev-smartcard-reader.c index 12c82c8f6458..279fef03652b 100644 --- a/hw/usb/dev-smartcard-reader.c +++ b/hw/usb/dev-smartcard-reader.c @@ -765,13 +765,13 @@ static void ccid_write_parameters(USBCCIDState *s, CC= ID_Header *recv) usb_wakeup(s->bulk, 0); } =20 -static void ccid_write_data_block(USBCCIDState *s, uint8_t slot, uint8_t s= eq, +static bool ccid_write_data_block(USBCCIDState *s, uint8_t slot, uint8_t s= eq, const uint8_t *data, uint32_t len) { CCID_DataBlock *p =3D ccid_reserve_recv_buf(s, sizeof(*p) + len); =20 if (p =3D=3D NULL) { - return; + return false; } p->b.hdr.bMessageType =3D CCID_MESSAGE_TYPE_RDR_to_PC_DataBlock; p->b.hdr.dwLength =3D cpu_to_le32(len); @@ -788,6 +788,7 @@ static void ccid_write_data_block(USBCCIDState *s, uint= 8_t slot, uint8_t seq, } ccid_reset_error_status(s); usb_wakeup(s->bulk, 0); + return true; } =20 static void ccid_report_error_failed(USBCCIDState *s, uint8_t error) @@ -796,19 +797,26 @@ static void ccid_report_error_failed(USBCCIDState *s,= uint8_t error) s->bError =3D error; } =20 -static void ccid_write_data_block_answer(USBCCIDState *s, - const uint8_t *data, uint32_t len) +static Answer *ccid_peek_next_answer(USBCCIDState *s); + +static bool ccid_write_data_block_answer(USBCCIDState *s, + const uint8_t *data, uint32_t len) { - uint8_t seq; uint8_t slot; + uint8_t seq; + Answer *answer; =20 if (!ccid_has_pending_answers(s)) { DPRINTF(s, D_WARN, "error: no pending answer to return to guest\n"= ); ccid_report_error_failed(s, ERROR_ICC_MUTE); - return; + return false; + } + answer =3D ccid_peek_next_answer(s); + if (!ccid_write_data_block(s, answer->slot, answer->seq, data, len)) { + return false; } ccid_remove_pending_answer(s, &slot, &seq); - ccid_write_data_block(s, slot, seq, data, len); + return true; } =20 static uint8_t atr_get_protocol_num(const uint8_t *atr, uint32_t len) @@ -1008,6 +1016,18 @@ static void ccid_handle_bulk_out(USBCCIDState *s, US= BPacket *p) CCID_Header *ccid_header; uint32_t payload_len; =20 + /* + * Every accepted command either queues a response immediately or comm= its a + * slot to a later APDU response. Apply backpressure before consuming = the + * first packet when all response slots are committed. + */ + if (s->bulk_out_pos =3D=3D 0 && /* start of message */ + s->bulk_in_pending_num + s->pending_answers_num >=3D + BULK_IN_PENDING_NUM) { + p->status =3D USB_RET_NAK; + return; + } + if (p->iov.size + s->bulk_out_pos > BULK_OUT_DATA_SIZE) { goto err; } @@ -1190,7 +1210,9 @@ static void ccid_unrealize(USBDevice *dev) static void ccid_flush_pending_answers(USBCCIDState *s) { while (ccid_has_pending_answers(s)) { - ccid_write_data_block_answer(s, NULL, 0); + if (!ccid_write_data_block_answer(s, NULL, 0)) { + break; + } } } =20 --=20 2.55.0