dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel()grafted

When dma_device_put() drops the last reference on chan->device->ref,
dma_device_release() runs and may free the dma_device along with its
channels.

dma_chan_put() then still reads chan->device->owner via
dma_chan_to_owner() for the trailing module_put(). KASAN catches it:

	slab-use-after-free in dma_chan_put+0x3e6/0x4c0
	Read of size 8 by task insmod/6319
	Freed by task 6319:
	  kfree+0x225/0x470
	  dma_chan_put+0x395/0x4c0
	  dmaengine_put+0xf8/0x160

Cache the module owner in dma_chan_put() before the put so the trailing
module_put() does not need chan->device.

Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct")
Suggested-by: Sashiko <sashiko-bot@kernel.org>
Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Shivank Garg <shivankg@amd.com>
Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 76 insertions, 0 deletions

diff --git a/scripts/checkversion.pl b/scripts/checkversion.pl
new file mode 100755
index 000000000..94cd49eff
--- /dev/null
+++ b/scripts/checkversion.pl
@@ -0,0 +1,76 @@
+#! /usr/bin/env perl
+# SPDX-License-Identifier: GPL-2.0
+#
+# checkversion finds uses of all macros in <linux/version.h>
+# where the source files do not #include <linux/version.h>; or cases
+# of including <linux/version.h> where it is not needed.
+# Copyright (C) 2003, Randy Dunlap <rdunlap@infradead.org>
+
+use strict;
+
+$| = 1;
+
+my $debugging;
+
+foreach my $file (@ARGV) {
+    next if $file =~ "include/generated/uapi/linux/version\.h";
+    next if $file =~ "usr/include/linux/version\.h";
+    # Open this file.
+    open( my $f, '<', $file )
+      or die "Can't open $file: $!\n";
+
+    # Initialize variables.
+    my ($fInComment, $fInString, $fUseVersion);
+    my $iLinuxVersion = 0;
+
+    while (<$f>) {
+	# Strip comments.
+	$fInComment && (s+^.*?\*/+ +o ? ($fInComment = 0) : next);
+	m+/\*+o && (s+/\*.*?\*/+ +go, (s+/\*.*$+ +o && ($fInComment = 1)));
+
+	# Pick up definitions.
+	if ( m/^\s*#/o ) {
+	    $iLinuxVersion      = $. if m/^\s*#\s*include\s*"linux\/version\.h"/o;
+	}
+
+	# Strip strings.
+	$fInString && (s+^.*?"+ +o ? ($fInString = 0) : next);
+	m+"+o && (s+".*?"+ +go, (s+".*$+ +o && ($fInString = 1)));
+
+	# Pick up definitions.
+	if ( m/^\s*#/o ) {
+	    $iLinuxVersion      = $. if m/^\s*#\s*include\s*<linux\/version\.h>/o;
+	}
+
+	# Look for uses: LINUX_VERSION_CODE, KERNEL_VERSION,
+	# LINUX_VERSION_MAJOR, LINUX_VERSION_PATCHLEVEL, LINUX_VERSION_SUBLEVEL
+	if (($_ =~ /LINUX_VERSION_CODE/) || ($_ =~ /\WKERNEL_VERSION/) ||
+	    ($_ =~ /LINUX_VERSION_MAJOR/) || ($_ =~ /LINUX_VERSION_PATCHLEVEL/) ||
+	    ($_ =~ /LINUX_VERSION_SUBLEVEL/)) {
+	    $fUseVersion = 1;
+            last if $iLinuxVersion;
+        }
+    }
+
+    # Report used version IDs without include?
+    if ($fUseVersion && ! $iLinuxVersion) {
+	print "$file: $.: need linux/version.h\n";
+    }
+
+    # Report superfluous includes.
+    if ($iLinuxVersion && ! $fUseVersion) {
+	print "$file: $iLinuxVersion linux/version.h not needed.\n";
+    }
+
+    # debug: report OK results:
+    if ($debugging) {
+        if ($iLinuxVersion && $fUseVersion) {
+	    print "$file: version use is OK ($iLinuxVersion)\n";
+        }
+        if (! $iLinuxVersion && ! $fUseVersion) {
+	    print "$file: version use is OK (none)\n";
+        }
+    }
+
+    close($f);
+}