[PATCH 6.18.y 4/5] cifs: SMB1 split: Separate out SMB1 decls into smb1proto.h

[Sasha Levin]

From: David Howells <dhowells@xxxxxxxxxx>

[ Upstream commit 645427b7a6c59e0074df29bf939aec2e9d6f2819 ]

Separate out SMB1 declarations scriptedly into smb1proto.h.  Script below:

	#!/usr/bin/perl -w
	use strict;
	unless (@ARGV) {
	    die "Usage: $0 <c_file1> [<c_file2> ...]\n";
	}

	# Data tracking
	my %funcs = ();		# Func name => { func prototype }
	my %headers = ();	# Header filename => { header content }
	my %c_files = ();	# C filename => { ordered func list, header pref }
	my %cmarkers = ();	# C filename marker => { header filename it's in }

	# Parse state
	my $pathname = "-";
	my $lineno = 0;

	sub error(@) {
	    print STDERR $pathname, ":", $lineno, ": ", @_, "\n";
	    exit(1);
	}

	sub pad($) {
	    # Reindent the function arguments to line the arguments up with the char
	    # after the opening bracket on the func argument list
	    my ($lines) = @_;
	    return $lines if ($#{$lines} <= 0);
	    my $has_empty = 0;
	    for (my $i = 0; $i <= $#{$lines}; $i++) {
		$lines->[$i] =~ s/^[ \t]+//;
		$has_empty = 1 if ($lines->[$i] eq "");
	    }

	    if ($has_empty) {
		my @clean = grep /.+/, @{$lines};
		$lines = \@clean;
	    }

	    my $indlen = index($lines->[0], "(");
	    return $lines if ($indlen < 0);
	    my $indent = "";
	    $indlen++;
	    $indent .= "\t" x ($indlen / 8);
	    $indent .= " " x ($indlen % 8);

	    my @padded = ();
	    my $acc = "";
	    my $len = -$indlen;
	    for (my $i = 0; $i <= $#{$lines}; $i++) {
		my $argument = $lines->[$i];
		my $arglen = length($argument);
		my $last = ($i == $#{$lines} ? 1 : 0);

		if ($i == 0 ||
		    $i == 1) {
		    $acc .= $argument;
		    $acc .= ";" if ($last);
		    $len += $arglen + $last;
		    next;
		}
		if (!$acc) {
		    $acc = $indent . $argument;
		    $acc .= ";" if ($last);
		    $len += $arglen + $last;
		    next;
		}
		if ($indlen + $len + 1 + $arglen + $last > 79) {
		    push @padded, $acc;
		    $acc = $indent . $argument;
		    $acc .= ";" if ($last);
		    $len = $arglen + $last;
		    next;
		}

		$acc .= " " . $argument;
		$acc .= ";" if ($last);
		$len += 1 + $arglen + $last;
	    }
	    push @padded, $acc if ($acc);
	    return \@padded;
	}

	sub earliest(@) {
	    my $ret = -1;
	    foreach (@_) {
		$ret = $_ if ($ret < 0 || ($_ >= 0 && $_ < $ret));
	    }
	    return $ret;
	}

	foreach my $file (@ARGV) {
	    # Open the file for reading.
	    next if $file =~ /trace[.]h$/;
	    next if $file =~ /smbdirect[.][ch]$/;
	    open my $fh, "<$file"
		or die "Could not open file '$file'";
	    $pathname = $file;
	    $lineno = 0;

	    my $filename;
	    my @file_content = ();
	    my @copy = ();

	    my $state = 0;
	    my $qual = "";
	    my $type = "";
	    my $funcname = "";
	    my @funcdef = ();
	    my $bracket = 0;
	    my $comment = 0;
	    my $smb1 = 0;
	    my $header = 0;
	    my $inline = 0;
	    my $file_marker = "";
	    my $config = "";
	    my $c_file = 0;

	    $filename = $pathname;
	    $filename =~ s!.*/!!;

	    if ($file =~ m!.h$!) {
		my %new_h_file = (
		    path    => $pathname,
		    fname   => $filename,
		    content => [],
		    );
		$header = \%new_h_file;
		$headers{$filename} = \%new_h_file;
	    } elsif ($file =~ m!.c$!) {
		my %new_c_file = (
		    path  => $pathname,
		    fname => $filename,
		    funcs => [],
		    );
		$c_file = \%new_c_file;
		$c_files{$filename} = \%new_c_file;
	    } else {
		warn("Ignoring unexpected file $file\n");
		next;
	    }

	    $smb1 = 1 if ($file =~ m!/smb1ops.c|/cifssmb.c|/cifstransport.c!);

	    foreach my $line (<$fh>) {
		$lineno++;
		chomp($line);
		push @copy, $line;
		if (!$line) {
		    # Blank line
		    push @file_content, @copy;
		    @copy = ();
		    next;
		}

		# Handle continuation or end of block comment.  Look for C file
		# prototype insertion point markers.
		if ($comment) {
		    if ($line =~ m![*]/!) {
			if ($comment == 2 && $file_marker) {
			    $cmarkers{$file_marker} = $file_marker;
			    push @copy, "#C_MARKER " . $file_marker;
			    $file_marker = 0;
			}
			$comment = 0;
		    } else {
			$comment++;
			if ($comment == 2 && $line =~ m! [*] ([a-z][a-z_0-9]*[.][c])$!) {
			    $file_marker = $1;
			    print("Found file marker ", $file_marker, " in ", $filename, "\n");
			}
		    }
		    push @file_content, @copy;
		    @copy = ();
		    next;
		}

		# Check cpp directives, particularly looking for SMB1 bits
		if ($line =~ /^[#]/) {
		    if ($header) {
			if ($line =~ /ifdef.*(CONFIG_[A-Z0-9_])/) {
			    error("multiconfig") if $config;
			    $config = $1;
			    $smb1++ if ($config eq "CONFIG_CIFS_ALLOW_INSECURE_LEGACY");
			} elsif ($line =~ /endif/) {
			    $smb1-- if ($config eq "CONFIG_CIFS_ALLOW_INSECURE_LEGACY");
			    $config = "";
			}
		    }
		    push @file_content, @copy;
		    @copy = ();
		    next;
		}

		# Exclude interference in finding func names and return types
		if ($line =~ /^[{]/ ||
		    $line =~ /##/ ||
		    $line =~ /^[_a-z0-9A-Z]+:$/ || # goto label
		    $line =~ /^do [{]/ ||
		    $line =~ m!^//!) {
		    push @file_content, @copy;
		    @copy = ();
		    next;
		}

		# Start of a block comment
		if ($line =~ m!^/[*]!) {
		    $comment = 1 unless ($line =~ m![*]/!);
		    push @file_content, @copy;
		    @copy = ();
		    next;
		}

		# End of a braced section, such as a function implementation
		if ($line =~ /^[}]/) {
			$type = "";
			$qual = "";
			$funcname = "";
			@funcdef = ();
			push @file_content, @copy;
			@copy = ();
			next;
		}

		if ($line =~ /^typedef/) {
		    $type = "";
		    $qual = "";
		    $funcname = "";
		    @funcdef = ();
		    push @file_content, @copy;
		    @copy = ();
		    next;
		}

		# Extract function qualifiers.  There may be multiple of these in more
		# or less any order.  Some of them cause the func to be skipped (e.g. inline).

		if ($line =~ /^(static|extern|inline|noinline|noinline_for_stack|__always_inline)\W/ ||
		    $line =~ /^(static|extern|inline|noinline|noinline_for_stack|__always_inline)$/) {
		    error("Unexpected qualifier '$1'") if ($state != 0);
		    while ($line =~ /^(static|extern|inline|noinline|noinline_for_stack|__always_inline)\W/ ||
			   $line =~ /^(static|extern|inline|noinline|noinline_for_stack|__always_inline)$/) {
			$qual .= " " if ($qual);
			$qual .= $1;
			$inline = 1 if ($1 eq "inline");
			$inline = 1 if ($1 eq "__always_inline");
			$line = substr($line, length($1));
			$line =~ s/^\s+//;
		    }
		}

		if ($state == 0) {
		    # Extract what we assume to be the return type
		    if ($line =~ /^\s/) {
			push @file_content, @copy;
			@copy = ();
			next;
		    }
		    while ($line =~ /^(unsigned|signed|bool|char|short|int|long|void|const|volatile|(struct|union|enum)\s+[_a-zA-Z][_a-zA-Z0-9]*|[*]|__init|__exit|__le16|__le32|__le64|__be16|__be32|__be64)/) {
			$type .= " " if $type;
			$type .= $1;
			$line = substr($line, length($1));
			$line =~ s/^\s+//;
		    }
		    if ($line =~ /^struct [{]/) {
			# Ignore structure definitions
			$type = "";
			$qual = "";
			$funcname = "";
			@funcdef = ();
			push @file_content, @copy;
			@copy = ();
			next;
		    }
		    if (index($line, "=") >= 0) {
			# Ignore assignments
			$type = "";
			$qual = "";
			$funcname = "";
			@funcdef = "";
			push @file_content, @copy;
			@copy = ();
			next;
		    }

		    # Try and extract a function's type and name
		    while ($line =~ /(^[_a-zA-Z][_a-zA-Z0-9]*)/) {
			my $name = $1;
			$line = substr($line, length($name));
			next if ($line =~ /^[{]/);
			$line =~ s/^\s+//;

			my $ch = substr($line, 0, 1);
			last if ($ch eq "[" || $ch eq ";"); # Global variables

			if ($ch eq "(") {
			    # Found the function name
			    $state = 1;
			    $line = substr($line, 1);
			    $funcname = $name;
			    my $tmp = $qual . $type . " " . $funcname . "(";
			    $tmp =~ s/[*] /*/;
			    push @funcdef, $tmp;
			    $bracket = 1;
			    last;
			}

			if ($type) {
			    last if (index($line, ";") >= 0 && index($line, "(") == -1);
			    error("Unexpected name '$name' after '$type'");
			}

			$type .= " " if $type;
			$type .= $name;
			if ($line =~ /^(\s*[*]+)/) {
			    my $ptr = $1;
			    $type .= $ptr;
			    $line = substr($line, length($ptr));
			}
		    }
		}

		# Try and extract a function's argument list
		my $from = 0;
		if ($state == 1) {
		    while (1) {
			my $o = index($line, "(", $from);
			my $c = index($line, ")", $from);
			my $m = index($line, ",", $from);

			my $b = earliest($o, $c, $m);
			if ($b < 0) {
			    push @funcdef, $line
				unless ($line eq "");
			    last;
			}
			my $ch = substr($line, $b, 1);

			# Push the arguments separately on to the list
			if ($ch eq ",") {
			    push @funcdef, substr($line, 0, $b + 1);
			    $line = substr($line, $b + 1);
			    $from = 0;
			} elsif ($ch eq "(") {
			    # Handle brackets in the argument list (e.g. function
			    # pointers)
			    $bracket++;
			    $from = $b + 1;
			} elsif ($ch eq ")") {
			    $bracket--;
			    if ($bracket == 0) {
				push @funcdef, substr($line, 0, $b + 1);
				$line = substr($line, $b + 1);
				$state = 2;
				last;
			    }
			    $from = $b + 1;
			}
		    }
		}

		if ($state == 2) {
		    $inline = 1 if ($qual =~ /inline/);
		    #print("QUAL $qual $type $funcname $inline ", $#funcdef, "\n");
		    if (!$header &&
			$qual !~ /static/ &&
			$funcname ne "__acquires" &&
			$funcname ne "__releases" &&
			$funcname ne "module_init" &&
			$funcname ne "module_exit" &&
			$funcname ne "module_param" &&
			$funcname ne "module_param_call" &&
			$funcname ne "PROC_FILE_DEFINE" &&
			$funcname !~ /MODULE_/ &&
			$funcname !~ /DEFINE_/) {

			# Okay, we appear to have a function implementation
			my $func;
			my $dup = 0;

			if (exists($funcs{$funcname})) {
			    $func = $funcs{$funcname};
			    if (exists $func->{body}) {
				print("dup $funcname\n");
				$dup = 1;
			    }
			} else {
			    my %new_func = (
				name => $funcname,
				cond => "",
				legacy => 0,
				);
			    $func = \%new_func;
			    $funcs{$funcname} = $func;
			    $func->{body} = pad(\@funcdef);
			}
			$func->{body} = pad(\@funcdef);
			$func->{legacy} = 1 if $smb1;

			if ($funcname eq "cifs_inval_name_dfs_link_error") {
			    $func->{cond} = "#ifdef CONFIG_CIFS_DFS_UPCALL";
			} elsif ($funcname eq "cifs_listxattr") {
			    $func->{cond} = "#ifdef CONFIG_CIFS_XATTR";
			}

			push @{$c_file->{funcs}}, $func
			    unless $dup;
		    } elsif (!$header || $inline) {
			# Ignore inline function implementations and other weirdies
			push @file_content, @copy;
		    } elsif ($header && !$inline) {
			push @file_content, "#FUNCPROTO " . $funcname;

			my $func;

			if (exists($funcs{$funcname})) {
			    $func = $funcs{$funcname};
			    $func->{lineno} = $lineno;
			    $func->{pathname} = $pathname;
			} else {
			    my %new_func = (
				name => $funcname,
				cond => "",
				lineno => $lineno,
				pathname => $pathname,
				legacy => 0,
				);
			    $func = \%new_func;
			    $funcs{$funcname} = $func;
			}

			$func->{legacy} = 1 if $smb1;
		    }

		    @funcdef = ();
		    $type = "";
		    $qual = "";
		    $funcname = "";
		    $inline = 0;
		    $state = 0;
		    @copy = ();
		}
		if ($line =~ /;/) {
		    $type = "";
		    $qual = "";
		    $funcname = "";
		    @funcdef = ();
		    $state = 0;
		    push @file_content, @copy;
		    @copy = ();
		}
	    }
	    close($fh);

	    if ($header) {
		$header->{content} = \@file_content;
	    }
	}

	sub write_header($)
	{
	    my ($header) = @_;
	    my $path = $header->{path};
	    my $legacy = 0;

	    $legacy = 1 if ($path =~ m!smb1proto[.]h!);

	    my @output = ();

	    foreach my $line (@{$header->{content}}) {
		if ($line =~ "^[#]C_MARKER (.*)") {
		    my $file_marker = $cmarkers{$1};
		    my $c_file = $c_files{$file_marker};
		    print("Found $line\n");
		    foreach my $func (@{$c_file->{funcs}}) {
			print("func ", $func->{name}, "\n");
			push @output, @{$func->{body}};
		    }
		    next;
		} elsif ($line =~ "^[#]FUNCPROTO ([_a-zA-Z0-9]+)") {
		    my $funcname = $1;
		    my $func = $funcs{$funcname};
		    if (!$func->{body}) {
			print($func->{pathname}, ":", $func->{lineno}, ": '", $funcname,
			      "' dead prototype\n");
			next;
		    }
		    if ($func->{legacy} == $legacy) {
			#push @output, $line;
			push @output, @{$func->{body}};
		    }
		} else {
		    push @output, $line;
		}
	    }

	    open my $fh, ">$path"
		or die "Could not open file '$path' for writing";
	    foreach my $f (@output) {
		print($fh $f, "\n") or die $path;
	    }
	    close($fh) or die $path;
	}

	foreach my $h (keys(%headers)) {
	    write_header($headers{$h});
	}

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Steve French <sfrench@xxxxxxxxx>
cc: Paulo Alcantara <pc@xxxxxxxxxxxxx>
cc: Enzo Matsumiya <ematsumiya@xxxxxxx>
cc: linux-cifs@xxxxxxxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
cc: linux-kernel@xxxxxxxxxxxxxxx
Acked-by: Enzo Matsumiya <ematsumiya@xxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>

[ sashal: Reduced backport -- upstream 645427b7a6c59 touches 3 file(s), this
  backport carries 3. Not backported here:
  fs/smb/client/cifsproto.h
  fs/smb/client/fscache.h
  This note is generated from the file lists only; see the resolution record
  for the reasoning. ]

Stable-dep-of: 6343c1da5619 ("smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/smb/client/smb1ops.c       | 171 ----------------------------------
 fs/smb/client/smb1proto.h     |   2 +
 fs/smb/client/smb1transport.c | 171 ++++++++++++++++++++++++++++++++++
 3 files changed, 173 insertions(+), 171 deletions(-)

diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
index ca8f3dd7ff63b..5a500a5e138c1 100644
--- a/fs/smb/client/smb1ops.c
+++ b/fs/smb/client/smb1ops.c
@@ -238,146 +238,6 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 	return mid;
 }
 
-/*
-	return codes:
-		0	not a transact2, or all data present
-		>0	transact2 with that much data missing
-		-EINVAL	invalid transact2
- */
-static int
-check2ndT2(char *buf)
-{
-	struct smb_hdr *pSMB = (struct smb_hdr *)buf;
-	struct smb_t2_rsp *pSMBt;
-	int remaining;
-	__u16 total_data_size, data_in_this_rsp;
-
-	if (pSMB->Command != SMB_COM_TRANSACTION2)
-		return 0;
-
-	/* check for plausible wct, bcc and t2 data and parm sizes */
-	/* check for parm and data offset going beyond end of smb */
-	if (pSMB->WordCount != 10) { /* coalesce_t2 depends on this */
-		cifs_dbg(FYI, "Invalid transact2 word count\n");
-		return -EINVAL;
-	}
-
-	pSMBt = (struct smb_t2_rsp *)pSMB;
-
-	total_data_size = get_unaligned_le16(&pSMBt->t2_rsp.TotalDataCount);
-	data_in_this_rsp = get_unaligned_le16(&pSMBt->t2_rsp.DataCount);
-
-	if (total_data_size == data_in_this_rsp)
-		return 0;
-	else if (total_data_size < data_in_this_rsp) {
-		cifs_dbg(FYI, "total data %d smaller than data in frame %d\n",
-			 total_data_size, data_in_this_rsp);
-		return -EINVAL;
-	}
-
-	remaining = total_data_size - data_in_this_rsp;
-
-	cifs_dbg(FYI, "missing %d bytes from transact2, check next response\n",
-		 remaining);
-	if (total_data_size > CIFSMaxBufSize) {
-		cifs_dbg(VFS, "TotalDataSize %d is over maximum buffer %d\n",
-			 total_data_size, CIFSMaxBufSize);
-		return -EINVAL;
-	}
-	return remaining;
-}
-
-static int
-coalesce_t2(char *second_buf, struct smb_hdr *target_hdr)
-{
-	struct smb_t2_rsp *pSMBs = (struct smb_t2_rsp *)second_buf;
-	struct smb_t2_rsp *pSMBt  = (struct smb_t2_rsp *)target_hdr;
-	char *data_area_of_tgt;
-	char *data_area_of_src;
-	int remaining;
-	unsigned int byte_count, total_in_tgt;
-	__u16 tgt_total_cnt, src_total_cnt, total_in_src;
-
-	src_total_cnt = get_unaligned_le16(&pSMBs->t2_rsp.TotalDataCount);
-	tgt_total_cnt = get_unaligned_le16(&pSMBt->t2_rsp.TotalDataCount);
-
-	if (tgt_total_cnt != src_total_cnt)
-		cifs_dbg(FYI, "total data count of primary and secondary t2 differ source=%hu target=%hu\n",
-			 src_total_cnt, tgt_total_cnt);
-
-	total_in_tgt = get_unaligned_le16(&pSMBt->t2_rsp.DataCount);
-
-	remaining = tgt_total_cnt - total_in_tgt;
-
-	if (remaining < 0) {
-		cifs_dbg(FYI, "Server sent too much data. tgt_total_cnt=%hu total_in_tgt=%u\n",
-			 tgt_total_cnt, total_in_tgt);
-		return -EPROTO;
-	}
-
-	if (remaining == 0) {
-		/* nothing to do, ignore */
-		cifs_dbg(FYI, "no more data remains\n");
-		return 0;
-	}
-
-	total_in_src = get_unaligned_le16(&pSMBs->t2_rsp.DataCount);
-	if (remaining < total_in_src)
-		cifs_dbg(FYI, "transact2 2nd response contains too much data\n");
-
-	/* find end of first SMB data area */
-	data_area_of_tgt = (char *)&pSMBt->hdr.Protocol +
-				get_unaligned_le16(&pSMBt->t2_rsp.DataOffset);
-
-	/* validate target area */
-	data_area_of_src = (char *)&pSMBs->hdr.Protocol +
-				get_unaligned_le16(&pSMBs->t2_rsp.DataOffset);
-
-	data_area_of_tgt += total_in_tgt;
-
-	total_in_tgt += total_in_src;
-	/* is the result too big for the field? */
-	if (total_in_tgt > USHRT_MAX) {
-		cifs_dbg(FYI, "coalesced DataCount too large (%u)\n",
-			 total_in_tgt);
-		return -EPROTO;
-	}
-	put_unaligned_le16(total_in_tgt, &pSMBt->t2_rsp.DataCount);
-
-	/* fix up the BCC */
-	byte_count = get_bcc(target_hdr);
-	byte_count += total_in_src;
-	/* is the result too big for the field? */
-	if (byte_count > USHRT_MAX) {
-		cifs_dbg(FYI, "coalesced BCC too large (%u)\n", byte_count);
-		return -EPROTO;
-	}
-	put_bcc(byte_count, target_hdr);
-
-	byte_count = be32_to_cpu(target_hdr->smb_buf_length);
-	byte_count += total_in_src;
-	/* don't allow buffer to overflow */
-	if (byte_count > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) {
-		cifs_dbg(FYI, "coalesced BCC exceeds buffer size (%u)\n",
-			 byte_count);
-		return -ENOBUFS;
-	}
-	target_hdr->smb_buf_length = cpu_to_be32(byte_count);
-
-	/* copy second buffer into end of first buffer */
-	memcpy(data_area_of_tgt, data_area_of_src, total_in_src);
-
-	if (remaining != total_in_src) {
-		/* more responses to go */
-		cifs_dbg(FYI, "waiting for more secondary responses\n");
-		return 1;
-	}
-
-	/* we are done */
-	cifs_dbg(FYI, "found the last secondary response\n");
-	return 0;
-}
-
 static void
 cifs_downgrade_oplock(struct TCP_Server_Info *server,
 		      struct cifsInodeInfo *cinode, __u32 oplock,
@@ -386,37 +246,6 @@ cifs_downgrade_oplock(struct TCP_Server_Info *server,
 	cifs_set_oplock_level(cinode, oplock);
 }
 
-static bool
-cifs_check_trans2(struct mid_q_entry *mid, struct TCP_Server_Info *server,
-		  char *buf, int malformed)
-{
-	if (malformed)
-		return false;
-	if (check2ndT2(buf) <= 0)
-		return false;
-	mid->multiRsp = true;
-	if (mid->resp_buf) {
-		/* merge response - fix up 1st*/
-		malformed = coalesce_t2(buf, mid->resp_buf);
-		if (malformed > 0)
-			return true;
-		/* All parts received or packet is malformed. */
-		mid->multiEnd = true;
-		dequeue_mid(mid, malformed);
-		return true;
-	}
-	if (!server->large_buf) {
-		/*FIXME: switch to already allocated largebuf?*/
-		cifs_dbg(VFS, "1st trans2 resp needs bigbuf\n");
-	} else {
-		/* Have first buffer */
-		mid->resp_buf = buf;
-		mid->large_buf = true;
-		server->bigbuf = NULL;
-	}
-	return true;
-}
-
 static bool
 cifs_need_neg(struct TCP_Server_Info *server)
 {
diff --git a/fs/smb/client/smb1proto.h b/fs/smb/client/smb1proto.h
index a73213f6a2aa1..8dfc6976ceba1 100644
--- a/fs/smb/client/smb1proto.h
+++ b/fs/smb/client/smb1proto.h
@@ -33,6 +33,8 @@ extern struct smb_version_values smb1_values;
 /*
  * smb1transport.c
  */
+bool cifs_check_trans2(struct mid_q_entry *mid, struct TCP_Server_Info *server,
+		       char *buf, int malformed);
 
 #endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
 #endif /* _SMB1PROTO_H */
diff --git a/fs/smb/client/smb1transport.c b/fs/smb/client/smb1transport.c
index bafc5181e0292..f7b00bcb9df1a 100644
--- a/fs/smb/client/smb1transport.c
+++ b/fs/smb/client/smb1transport.c
@@ -563,3 +563,174 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 		return -ERESTARTSYS;
 	return rc;
 }
+
+/*
+	return codes:
+		0	not a transact2, or all data present
+		>0	transact2 with that much data missing
+		-EINVAL	invalid transact2
+ */
+static int
+check2ndT2(char *buf)
+{
+	struct smb_hdr *pSMB = (struct smb_hdr *)buf;
+	struct smb_t2_rsp *pSMBt;
+	int remaining;
+	__u16 total_data_size, data_in_this_rsp;
+
+	if (pSMB->Command != SMB_COM_TRANSACTION2)
+		return 0;
+
+	/* check for plausible wct, bcc and t2 data and parm sizes */
+	/* check for parm and data offset going beyond end of smb */
+	if (pSMB->WordCount != 10) { /* coalesce_t2 depends on this */
+		cifs_dbg(FYI, "Invalid transact2 word count\n");
+		return -EINVAL;
+	}
+
+	pSMBt = (struct smb_t2_rsp *)pSMB;
+
+	total_data_size = get_unaligned_le16(&pSMBt->t2_rsp.TotalDataCount);
+	data_in_this_rsp = get_unaligned_le16(&pSMBt->t2_rsp.DataCount);
+
+	if (total_data_size == data_in_this_rsp)
+		return 0;
+	else if (total_data_size < data_in_this_rsp) {
+		cifs_dbg(FYI, "total data %d smaller than data in frame %d\n",
+			 total_data_size, data_in_this_rsp);
+		return -EINVAL;
+	}
+
+	remaining = total_data_size - data_in_this_rsp;
+
+	cifs_dbg(FYI, "missing %d bytes from transact2, check next response\n",
+		 remaining);
+	if (total_data_size > CIFSMaxBufSize) {
+		cifs_dbg(VFS, "TotalDataSize %d is over maximum buffer %d\n",
+			 total_data_size, CIFSMaxBufSize);
+		return -EINVAL;
+	}
+	return remaining;
+}
+
+static int
+coalesce_t2(char *second_buf, struct smb_hdr *target_hdr)
+{
+	struct smb_t2_rsp *pSMBs = (struct smb_t2_rsp *)second_buf;
+	struct smb_t2_rsp *pSMBt  = (struct smb_t2_rsp *)target_hdr;
+	char *data_area_of_tgt;
+	char *data_area_of_src;
+	int remaining;
+	unsigned int byte_count, total_in_tgt;
+	__u16 tgt_total_cnt, src_total_cnt, total_in_src;
+
+	src_total_cnt = get_unaligned_le16(&pSMBs->t2_rsp.TotalDataCount);
+	tgt_total_cnt = get_unaligned_le16(&pSMBt->t2_rsp.TotalDataCount);
+
+	if (tgt_total_cnt != src_total_cnt)
+		cifs_dbg(FYI, "total data count of primary and secondary t2 differ source=%hu target=%hu\n",
+			 src_total_cnt, tgt_total_cnt);
+
+	total_in_tgt = get_unaligned_le16(&pSMBt->t2_rsp.DataCount);
+
+	remaining = tgt_total_cnt - total_in_tgt;
+
+	if (remaining < 0) {
+		cifs_dbg(FYI, "Server sent too much data. tgt_total_cnt=%hu total_in_tgt=%u\n",
+			 tgt_total_cnt, total_in_tgt);
+		return -EPROTO;
+	}
+
+	if (remaining == 0) {
+		/* nothing to do, ignore */
+		cifs_dbg(FYI, "no more data remains\n");
+		return 0;
+	}
+
+	total_in_src = get_unaligned_le16(&pSMBs->t2_rsp.DataCount);
+	if (remaining < total_in_src)
+		cifs_dbg(FYI, "transact2 2nd response contains too much data\n");
+
+	/* find end of first SMB data area */
+	data_area_of_tgt = (char *)&pSMBt->hdr.Protocol +
+				get_unaligned_le16(&pSMBt->t2_rsp.DataOffset);
+
+	/* validate target area */
+	data_area_of_src = (char *)&pSMBs->hdr.Protocol +
+				get_unaligned_le16(&pSMBs->t2_rsp.DataOffset);
+
+	data_area_of_tgt += total_in_tgt;
+
+	total_in_tgt += total_in_src;
+	/* is the result too big for the field? */
+	if (total_in_tgt > USHRT_MAX) {
+		cifs_dbg(FYI, "coalesced DataCount too large (%u)\n",
+			 total_in_tgt);
+		return -EPROTO;
+	}
+	put_unaligned_le16(total_in_tgt, &pSMBt->t2_rsp.DataCount);
+
+	/* fix up the BCC */
+	byte_count = get_bcc(target_hdr);
+	byte_count += total_in_src;
+	/* is the result too big for the field? */
+	if (byte_count > USHRT_MAX) {
+		cifs_dbg(FYI, "coalesced BCC too large (%u)\n", byte_count);
+		return -EPROTO;
+	}
+	put_bcc(byte_count, target_hdr);
+
+	byte_count = be32_to_cpu(target_hdr->smb_buf_length);
+	byte_count += total_in_src;
+	/* don't allow buffer to overflow */
+	if (byte_count > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) {
+		cifs_dbg(FYI, "coalesced BCC exceeds buffer size (%u)\n",
+			 byte_count);
+		return -ENOBUFS;
+	}
+	target_hdr->smb_buf_length = cpu_to_be32(byte_count);
+
+	/* copy second buffer into end of first buffer */
+	memcpy(data_area_of_tgt, data_area_of_src, total_in_src);
+
+	if (remaining != total_in_src) {
+		/* more responses to go */
+		cifs_dbg(FYI, "waiting for more secondary responses\n");
+		return 1;
+	}
+
+	/* we are done */
+	cifs_dbg(FYI, "found the last secondary response\n");
+	return 0;
+}
+
+bool
+cifs_check_trans2(struct mid_q_entry *mid, struct TCP_Server_Info *server,
+		  char *buf, int malformed)
+{
+	if (malformed)
+		return false;
+	if (check2ndT2(buf) <= 0)
+		return false;
+	mid->multiRsp = true;
+	if (mid->resp_buf) {
+		/* merge response - fix up 1st*/
+		malformed = coalesce_t2(buf, mid->resp_buf);
+		if (malformed > 0)
+			return true;
+		/* All parts received or packet is malformed. */
+		mid->multiEnd = true;
+		dequeue_mid(mid, malformed);
+		return true;
+	}
+	if (!server->large_buf) {
+		/*FIXME: switch to already allocated largebuf?*/
+		cifs_dbg(VFS, "1st trans2 resp needs bigbuf\n");
+	} else {
+		/* Have first buffer */
+		mid->resp_buf = buf;
+		mid->large_buf = true;
+		server->bigbuf = NULL;
+	}
+	return true;
+}
-- 
2.53.0