The ttusb_dec_send_command() function allocates a 64-byte buffer (COMMAND_PACKET_SIZE + 4) for USB communication. After receiving a response, it reads the payload length from b[3] (which is fully controlled by the USB device) and copies the payload into the caller-provided cmd_result buffer. There are two missing bounds checks. First, b[3] can be up to 255, exceeding the 60-byte payload capacity of the allocated buffer, leading to an out-of-bounds read. Second, the size of cmd_result is not passed to the function, so a large b[3] can cause a buffer overflow in the destination buffer (e.g., a 4-byte buffer in ttusbdecfe_dvbt_read_status()). This can result in a fortify panic: memcpy: detected buffer overflow: 75 byte read of buffer size 60 WARNING: lib/string_helpers.c:1037 at __fortify_report+0xa0/0xb8 lib/string_helpers.c:1036 ... Call trace: __fortify_report+0xa0/0xb8 lib/string_helpers.c:1036 (P) __fortify_panic+0x10/0x14 lib/string_helpers.c:1043 fortify_memcpy_chk include/linux/fortify-string.h:549 [inline] ttusb_dec_start_feed+0x0/0x10ac drivers/media/usb/ttusb-dec/ttusb_dec.c:372 ttusb_dec_get_stb_state drivers/media/usb/ttusb-dec/ttusb_dec.c:392 [inline] ttusb_dec_init_stb drivers/media/usb/ttusb-dec/ttusb_dec.c:1413 [inline] ttusb_dec_probe+0x724/0x1aa0 drivers/media/usb/ttusb-dec/ttusb_dec.c:1671 Fix this by adding a cmd_result_len parameter to ttusb_dec_send_command() and the send_command callback in ttusbdecfe_config. Update all callers to pass the correct buffer size. Inside ttusb_dec_send_command(), validate param_length, ensure actual_len is at least 4 bytes, and check that b[3] does not exceed COMMAND_PACKET_SIZE, actual_len - 4, or cmd_result_len. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Assisted-by: Gemini:gemini-3.6-flash Gemini:gemini-3.1-pro-preview syzbot Reported-by: syzbot+e1dbaae5eefaa2dfbc35@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=e1dbaae5eefaa2dfbc35 Link: https://syzkaller.appspot.com/ai_job?id=372cefef-e134-4934-87ec-0fbe6dfbc958 To: To: "Mauro Carvalho Chehab" To: "Linus Torvalds" Cc: "Kees Cook" Cc: --- diff --git a/drivers/media/usb/ttusb-dec/ttusb_dec.c b/drivers/media/usb/ttusb-dec/ttusb_dec.c index 825a38759..b54b7b4bb 100644 --- a/drivers/media/usb/ttusb-dec/ttusb_dec.c +++ b/drivers/media/usb/ttusb-dec/ttusb_dec.c @@ -314,13 +314,17 @@ static u16 crc16(u16 crc, const u8 *buf, size_t len) static int ttusb_dec_send_command(struct ttusb_dec *dec, const u8 command, int param_length, const u8 params[], - int *result_length, u8 cmd_result[]) + int *result_length, u8 cmd_result[], + int cmd_result_len) { int result, actual_len; u8 *b; dprintk("%s\n", __func__); + if (param_length > COMMAND_PACKET_SIZE) + return -EINVAL; + b = kzalloc(COMMAND_PACKET_SIZE + 4, GFP_KERNEL); if (!b) return -ENOMEM; @@ -366,10 +370,25 @@ static int ttusb_dec_send_command(struct ttusb_dec *dec, const u8 command, __func__, actual_len, b); } + if (actual_len < 4) { + result = -EIO; + goto err_mutex_unlock; + } + + if (b[3] > COMMAND_PACKET_SIZE || b[3] > actual_len - 4) { + result = -EIO; + goto err_mutex_unlock; + } + if (result_length) *result_length = b[3]; - if (cmd_result && b[3] > 0) + if (cmd_result && b[3] > 0) { + if (b[3] > cmd_result_len) { + result = -EIO; + goto err_mutex_unlock; + } memcpy(cmd_result, &b[4], b[3]); + } } err_mutex_unlock: @@ -389,7 +408,8 @@ static int ttusb_dec_get_stb_state (struct ttusb_dec *dec, unsigned int *mode, dprintk("%s\n", __func__); - result = ttusb_dec_send_command(dec, 0x08, 0, NULL, &c_length, c); + result = ttusb_dec_send_command(dec, 0x08, 0, NULL, &c_length, c, + sizeof(c)); if (result) return result; @@ -448,7 +468,7 @@ static void ttusb_dec_set_pids(struct ttusb_dec *dec) memcpy(&b[2], &audio, 2); memcpy(&b[4], &video, 2); - ttusb_dec_send_command(dec, 0x50, sizeof(b), b, NULL, NULL); + ttusb_dec_send_command(dec, 0x50, sizeof(b), b, NULL, NULL, 0); dvb_filter_pes2ts_init(&dec->a_pes2ts, dec->pid[DMX_PES_AUDIO], ttusb_dec_audio_pes2ts_cb, dec); @@ -902,7 +922,7 @@ static int ttusb_dec_set_interface(struct ttusb_dec *dec, break; case TTUSB_DEC_INTERFACE_IN: result = ttusb_dec_send_command(dec, 0x80, sizeof(b), - b, NULL, NULL); + b, NULL, NULL, 0); if (result) return result; result = usb_set_interface(dec->udev, 0, 8); @@ -1021,7 +1041,7 @@ static int ttusb_dec_start_ts_feed(struct dvb_demux_feed *dvbdmxfeed) } - result = ttusb_dec_send_command(dec, 0x80, sizeof(b0), b0, NULL, NULL); + result = ttusb_dec_send_command(dec, 0x80, sizeof(b0), b0, NULL, NULL, 0); if (result) return result; @@ -1056,7 +1076,7 @@ static int ttusb_dec_start_sec_feed(struct dvb_demux_feed *dvbdmxfeed) memcpy(&b0[5], &dvbdmxfeed->filter->filter.filter_value[0], 1); result = ttusb_dec_send_command(dec, 0x60, sizeof(b0), b0, - &c_length, c); + &c_length, c, sizeof(c)); if (!result) { if (c_length == 2) { @@ -1114,7 +1134,7 @@ static int ttusb_dec_stop_ts_feed(struct dvb_demux_feed *dvbdmxfeed) struct ttusb_dec *dec = dvbdmxfeed->demux->priv; u8 b0[] = { 0x00 }; - ttusb_dec_send_command(dec, 0x81, sizeof(b0), b0, NULL, NULL); + ttusb_dec_send_command(dec, 0x81, sizeof(b0), b0, NULL, NULL, 0); dec->pva_stream_count--; @@ -1135,7 +1155,7 @@ static int ttusb_dec_stop_sec_feed(struct dvb_demux_feed *dvbdmxfeed) list_del(&finfo->filter_info_list); spin_unlock_irqrestore(&dec->filter_info_list_lock, flags); kfree(finfo); - ttusb_dec_send_command(dec, 0x62, sizeof(b0), b0, NULL, NULL); + ttusb_dec_send_command(dec, 0x62, sizeof(b0), b0, NULL, NULL, 0); dec->filter_stream_count--; @@ -1238,7 +1258,7 @@ static int ttusb_init_rc( struct ttusb_dec *dec) if (usb_submit_urb(dec->irq_urb, GFP_KERNEL)) printk("%s: usb_submit_urb failed\n",__func__); /* enable irq pipe */ - ttusb_dec_send_command(dec,0xb0,sizeof(b),b,NULL,NULL); + ttusb_dec_send_command(dec, 0xb0, sizeof(b), b, NULL, NULL, 0); return 0; } @@ -1354,7 +1374,7 @@ static int ttusb_dec_boot_dsp(struct ttusb_dec *dec) firmware_csum_ns = htons(firmware_csum); memcpy(&b0[6], &firmware_csum_ns, 2); - result = ttusb_dec_send_command(dec, 0x41, sizeof(b0), b0, NULL, NULL); + result = ttusb_dec_send_command(dec, 0x41, sizeof(b0), b0, NULL, NULL, 0); if (result) { release_firmware(fw_entry); @@ -1395,7 +1415,7 @@ static int ttusb_dec_boot_dsp(struct ttusb_dec *dec) } } - result = ttusb_dec_send_command(dec, 0x43, sizeof(b1), b1, NULL, NULL); + result = ttusb_dec_send_command(dec, 0x43, sizeof(b1), b1, NULL, NULL, 0); release_firmware(fw_entry); kfree(b); @@ -1621,10 +1641,13 @@ static void ttusb_dec_exit_filters(struct ttusb_dec *dec) static int fe_send_command(struct dvb_frontend* fe, const u8 command, int param_length, const u8 params[], - int *result_length, u8 cmd_result[]) + int *result_length, u8 cmd_result[], + int cmd_result_len) { struct ttusb_dec* dec = fe->dvb->priv; - return ttusb_dec_send_command(dec, command, param_length, params, result_length, cmd_result); + return ttusb_dec_send_command(dec, command, param_length, params, + result_length, cmd_result, + cmd_result_len); } static const struct ttusbdecfe_config fe_config = { diff --git a/drivers/media/usb/ttusb-dec/ttusbdecfe.c b/drivers/media/usb/ttusb-dec/ttusbdecfe.c index 215221370..b013d6dfc 100644 --- a/drivers/media/usb/ttusb-dec/ttusbdecfe.c +++ b/drivers/media/usb/ttusb-dec/ttusbdecfe.c @@ -44,7 +44,8 @@ static int ttusbdecfe_dvbt_read_status(struct dvb_frontend *fe, *status=0; - ret=state->config->send_command(fe, 0x73, sizeof(b), b, &len, result); + ret = state->config->send_command(fe, 0x73, sizeof(b), b, &len, result, + sizeof(result)); if(ret) return ret; @@ -85,7 +86,7 @@ static int ttusbdecfe_dvbt_set_frontend(struct dvb_frontend *fe) __be32 freq = htonl(p->frequency / 1000); memcpy(&b[4], &freq, sizeof (u32)); - state->config->send_command(fe, 0x71, sizeof(b), b, NULL, NULL); + state->config->send_command(fe, 0x71, sizeof(b), b, NULL, NULL, 0); return 0; } @@ -130,7 +131,7 @@ static int ttusbdecfe_dvbs_set_frontend(struct dvb_frontend *fe) lnb_voltage = htonl(state->voltage); memcpy(&b[28], &lnb_voltage, sizeof(u32)); - state->config->send_command(fe, 0x71, sizeof(b), b, NULL, NULL); + state->config->send_command(fe, 0x71, sizeof(b), b, NULL, NULL, 0); return 0; } @@ -149,7 +150,7 @@ static int ttusbdecfe_dvbs_diseqc_send_master_cmd(struct dvb_frontend* fe, struc state->config->send_command(fe, 0x72, sizeof(b) - (6 - cmd->msg_len), b, - NULL, NULL); + NULL, NULL, 0); return 0; } diff --git a/drivers/media/usb/ttusb-dec/ttusbdecfe.h b/drivers/media/usb/ttusb-dec/ttusbdecfe.h index 73828bb22..96600ad4c 100644 --- a/drivers/media/usb/ttusb-dec/ttusbdecfe.h +++ b/drivers/media/usb/ttusb-dec/ttusbdecfe.h @@ -14,7 +14,8 @@ struct ttusbdecfe_config { int (*send_command)(struct dvb_frontend* fe, const u8 command, int param_length, const u8 params[], - int *result_length, u8 cmd_result[]); + int *result_length, u8 cmd_result[], + int cmd_result_len); }; extern struct dvb_frontend* ttusbdecfe_dvbs_attach(const struct ttusbdecfe_config* config); base-commit: 8d3ae59288f1e7d58d76558a6ee96d533bc5019f -- This is an AI-generated patch subject to moderation. 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