From: A Sun as1033x@comcast.net
commit e43148645d18efc3072b1ba45afaa3f385299e55 upstream.
Fix multiple cases of out of bounds (OOB) read associated with MCE device receive/input data handling.
In reference for the OOB cases below, the incoming/read (byte) data format when the MCE device responds to a command is: { cmd_prefix, subcmd, data0, data1, ... } where cmd_prefix are: MCE_CMD_PORT_SYS MCE_CMD_PORT_IR and subcmd examples are: MCE_RSP_GETPORTSTATUS MCE_RSP_EQIRNUMPORTS ... Response size dynamically depends on cmd_prefix and subcmd. So data0, data1, ... may or may not be present on input. Multiple responses may return in a single receiver buffer.
The trigger condition for OOB read is typically random or corrupt input data that fills the mceusb receiver buffer.
Case 1:
mceusb_handle_command() reads data0 (var hi) and data1 (var lo) regardless of whether the response includes such data. If { cmd_prefix, subcmd } is at the end of the receiver buffer, read past end of buffer occurs.
This case was reported by KASAN: slab-out-of-bounds Read in mceusb_dev_recv https://syzkaller.appspot.com/bug?extid=c7fdb6cb36e65f2fe8c9
Fix: In mceusb_handle_command(), change variable hi and lo to pointers, and dereference only when required.
Case 2:
If response with data is truncated at end of buffer after { cmd_prefix, subcmd }, mceusb_handle_command() reads past end of buffer for data0, data1, ...
Fix: In mceusb_process_ir_data(), check response size with remaining buffer size before invoking mceusb_handle_command(). + if (i + ir->rem < buf_len) mceusb_handle_command(ir, &ir->buf_in[i - 1]);
Case 3:
mceusb_handle_command() handles invalid/bad response such as { 0x??, MCE_RSP_GETPORTSTATUS } of length 2 as a response { MCE_CMD_PORT_SYS, MCE_RSP_GETPORTSTATUS, data0, ... } of length 7. Read OOB occurs for non-existent data0, data1, ... Cause is mceusb_handle_command() does not check cmd_prefix value.
Fix: mceusb_handle_command() must test both cmd_prefix and subcmd.
Case 4:
mceusb_process_ir_data() receiver parser state SUBCMD is possible at start (i=0) of receiver buffer resulting in buffer offset=-1 passed to mceusb_dev_printdata(). Bad offset results in OOB read before start of buffer.
[1214218.580308] mceusb 1-1.3:1.0: rx data[0]: 00 80 (length=2) [1214218.580323] mceusb 1-1.3:1.0: Unknown command 0x00 0x80 ... [1214218.580406] mceusb 1-1.3:1.0: rx data[14]: 7f 7f (length=2) [1214218.679311] mceusb 1-1.3:1.0: rx data[-1]: 80 90 (length=2) [1214218.679325] mceusb 1-1.3:1.0: End of raw IR data [1214218.679340] mceusb 1-1.3:1.0: rx data[1]: 7f 7f (length=2)
Fix: If parser_state is SUBCMD after processing receiver buffer, reset parser_state to CMD_HEADER. In effect, discard cmd_prefix at end of receiver buffer. In mceusb_dev_printdata(), abort if buffer offset is out of bounds.
Case 5:
If response with data is truncated at end of buffer after { cmd_prefix, subcmd }, mceusb_dev_printdata() reads past end of buffer for data0, data1, ... while decoding the response to print out.
Fix: In mceusb_dev_printdata(), remove unneeded buffer offset adjustments (var start and var skip) associated with MCE gen1 header. Test for truncated MCE cmd response (compare offset+len with buf_len) and skip decoding of incomplete response. Move IR data tracing to execute before the truncation test.
Signed-off-by: A Sun as1033x@comcast.net Signed-off-by: Sean Young sean@mess.org Signed-off-by: Mauro Carvalho Chehab mchehab+samsung@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/media/rc/mceusb.c | 141 +++++++++++++++++++++++++++++++--------------- 1 file changed, 98 insertions(+), 43 deletions(-)
--- a/drivers/media/rc/mceusb.c +++ b/drivers/media/rc/mceusb.c @@ -564,7 +564,7 @@ static int mceusb_cmd_datasize(u8 cmd, u datasize = 4; break; case MCE_CMD_G_REVISION: - datasize = 2; + datasize = 4; break; case MCE_RSP_EQWAKESUPPORT: case MCE_RSP_GETWAKESOURCE: @@ -600,14 +600,9 @@ static void mceusb_dev_printdata(struct char *inout; u8 cmd, subcmd, *data; struct device *dev = ir->dev; - int start, skip = 0; u32 carrier, period;
- /* skip meaningless 0xb1 0x60 header bytes on orig receiver */ - if (ir->flags.microsoft_gen1 && !out && !offset) - skip = 2; - - if (len <= skip) + if (offset < 0 || offset >= buf_len) return;
dev_dbg(dev, "%cx data[%d]: %*ph (len=%d sz=%d)", @@ -616,11 +611,32 @@ static void mceusb_dev_printdata(struct
inout = out ? "Request" : "Got";
- start = offset + skip; - cmd = buf[start] & 0xff; - subcmd = buf[start + 1] & 0xff; - data = buf + start + 2; + cmd = buf[offset]; + subcmd = (offset + 1 < buf_len) ? buf[offset + 1] : 0; + data = &buf[offset] + 2; + + /* Trace meaningless 0xb1 0x60 header bytes on original receiver */ + if (ir->flags.microsoft_gen1 && !out && !offset) { + dev_dbg(dev, "MCE gen 1 header"); + return; + }
+ /* Trace IR data header or trailer */ + if (cmd != MCE_CMD_PORT_IR && + (cmd & MCE_PORT_MASK) == MCE_COMMAND_IRDATA) { + if (cmd == MCE_IRDATA_TRAILER) + dev_dbg(dev, "End of raw IR data"); + else + dev_dbg(dev, "Raw IR data, %d pulse/space samples", + cmd & MCE_PACKET_LENGTH_MASK); + return; + } + + /* Unexpected end of buffer? */ + if (offset + len > buf_len) + return; + + /* Decode MCE command/response */ switch (cmd) { case MCE_CMD_NULL: if (subcmd == MCE_CMD_NULL) @@ -644,7 +660,7 @@ static void mceusb_dev_printdata(struct dev_dbg(dev, "Get hw/sw rev?"); else dev_dbg(dev, "hw/sw rev %*ph", - 4, &buf[start + 2]); + 4, &buf[offset + 2]); break; case MCE_CMD_RESUME: dev_dbg(dev, "Device resume requested"); @@ -746,13 +762,6 @@ static void mceusb_dev_printdata(struct default: break; } - - if (cmd == MCE_IRDATA_TRAILER) - dev_dbg(dev, "End of raw IR data"); - else if ((cmd != MCE_CMD_PORT_IR) && - ((cmd & MCE_PORT_MASK) == MCE_COMMAND_IRDATA)) - dev_dbg(dev, "Raw IR data, %d pulse/space samples", - cmd & MCE_PACKET_LENGTH_MASK); #endif }
@@ -1136,32 +1145,62 @@ static int mceusb_set_rx_carrier_report( }
/* + * Handle PORT_SYS/IR command response received from the MCE device. + * + * Assumes single response with all its data (not truncated) + * in buf_in[]. The response itself determines its total length + * (mceusb_cmd_datasize() + 2) and hence the minimum size of buf_in[]. + * * We don't do anything but print debug spew for many of the command bits * we receive from the hardware, but some of them are useful information * we want to store so that we can use them. */ -static void mceusb_handle_command(struct mceusb_dev *ir, int index) +static void mceusb_handle_command(struct mceusb_dev *ir, u8 *buf_in) { + u8 cmd = buf_in[0]; + u8 subcmd = buf_in[1]; + u8 *hi = &buf_in[2]; /* read only when required */ + u8 *lo = &buf_in[3]; /* read only when required */ struct ir_raw_event rawir = {}; - u8 hi = ir->buf_in[index + 1] & 0xff; - u8 lo = ir->buf_in[index + 2] & 0xff; u32 carrier_cycles; u32 cycles_fix;
- switch (ir->buf_in[index]) { - /* the one and only 5-byte return value command */ - case MCE_RSP_GETPORTSTATUS: - if ((ir->buf_in[index + 4] & 0xff) == 0x00) - ir->txports_cabled |= 1 << hi; - break; + if (cmd == MCE_CMD_PORT_SYS) { + switch (subcmd) { + /* the one and only 5-byte return value command */ + case MCE_RSP_GETPORTSTATUS: + if (buf_in[5] == 0) + ir->txports_cabled |= 1 << *hi; + break;
+ /* 1-byte return value commands */ + case MCE_RSP_EQEMVER: + ir->emver = *hi; + break; + + /* No return value commands */ + case MCE_RSP_CMD_ILLEGAL: + ir->need_reset = true; + break; + + default: + break; + } + + return; + } + + if (cmd != MCE_CMD_PORT_IR) + return; + + switch (subcmd) { /* 2-byte return value commands */ case MCE_RSP_EQIRTIMEOUT: - ir->rc->timeout = US_TO_NS((hi << 8 | lo) * MCE_TIME_UNIT); + ir->rc->timeout = US_TO_NS((*hi << 8 | *lo) * MCE_TIME_UNIT); break; case MCE_RSP_EQIRNUMPORTS: - ir->num_txports = hi; - ir->num_rxports = lo; + ir->num_txports = *hi; + ir->num_rxports = *lo; break; case MCE_RSP_EQIRRXCFCNT: /* @@ -1174,7 +1213,7 @@ static void mceusb_handle_command(struct */ if (ir->carrier_report_enabled && ir->learning_active && ir->pulse_tunit > 0) { - carrier_cycles = (hi << 8 | lo); + carrier_cycles = (*hi << 8 | *lo); /* * Adjust carrier cycle count by adding * 1 missed count per pulse "on" @@ -1192,24 +1231,24 @@ static void mceusb_handle_command(struct break;
/* 1-byte return value commands */ - case MCE_RSP_EQEMVER: - ir->emver = hi; - break; case MCE_RSP_EQIRTXPORTS: - ir->tx_mask = hi; + ir->tx_mask = *hi; break; case MCE_RSP_EQIRRXPORTEN: - ir->learning_active = ((hi & 0x02) == 0x02); - if (ir->rxports_active != hi) { + ir->learning_active = ((*hi & 0x02) == 0x02); + if (ir->rxports_active != *hi) { dev_info(ir->dev, "%s-range (0x%x) receiver active", - ir->learning_active ? "short" : "long", hi); - ir->rxports_active = hi; + ir->learning_active ? "short" : "long", *hi); + ir->rxports_active = *hi; } break; + + /* No return value commands */ case MCE_RSP_CMD_ILLEGAL: case MCE_RSP_TX_TIMEOUT: ir->need_reset = true; break; + default: break; } @@ -1235,7 +1274,8 @@ static void mceusb_process_ir_data(struc ir->rem = mceusb_cmd_datasize(ir->cmd, ir->buf_in[i]); mceusb_dev_printdata(ir, ir->buf_in, buf_len, i - 1, ir->rem + 2, false); - mceusb_handle_command(ir, i); + if (i + ir->rem < buf_len) + mceusb_handle_command(ir, &ir->buf_in[i - 1]); ir->parser_state = CMD_DATA; break; case PARSE_IRDATA: @@ -1264,15 +1304,22 @@ static void mceusb_process_ir_data(struc ir->rem--; break; case CMD_HEADER: - /* decode mce packets of the form (84),AA,BB,CC,DD */ - /* IR data packets can span USB messages - rem */ ir->cmd = ir->buf_in[i]; if ((ir->cmd == MCE_CMD_PORT_IR) || ((ir->cmd & MCE_PORT_MASK) != MCE_COMMAND_IRDATA)) { + /* + * got PORT_SYS, PORT_IR, or unknown + * command response prefix + */ ir->parser_state = SUBCMD; continue; } + /* + * got IR data prefix (0x80 + num_bytes) + * decode MCE packets of the form {0x83, AA, BB, CC} + * IR data packets can span USB messages + */ ir->rem = (ir->cmd & MCE_PACKET_LENGTH_MASK); mceusb_dev_printdata(ir, ir->buf_in, buf_len, i, ir->rem + 1, false); @@ -1296,6 +1343,14 @@ static void mceusb_process_ir_data(struc if (ir->parser_state != CMD_HEADER && !ir->rem) ir->parser_state = CMD_HEADER; } + + /* + * Accept IR data spanning multiple rx buffers. + * Reject MCE command response spanning multiple rx buffers. + */ + if (ir->parser_state != PARSE_IRDATA || !ir->rem) + ir->parser_state = CMD_HEADER; + if (event) { dev_dbg(ir->dev, "processed IR data"); ir_raw_event_handle(ir->rc);