[merged mm-hotfixes-stable] mm-damon-dbgfs-check-if-rm_contexts-input-is-for-a-real-context.patch removed from -mm tree

[merged mm-hotfixes-stable] mm-damon-dbgfs-check-if-rm_contexts-input-is-for-a-real-context.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/damon/dbgfs: check if rm_contexts input is for a real context
has been removed from the -mm tree.  Its filename was
     mm-damon-dbgfs-check-if-rm_contexts-input-is-for-a-real-context.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: SeongJae Park <sj@kernel.org>
Subject: mm/damon/dbgfs: check if rm_contexts input is for a real context
Date: Mon, 7 Nov 2022 16:50:00 +0000

A user could write a name of a file under 'damon/' debugfs directory,
which is not a user-created context, to 'rm_contexts' file.  In the case,
'dbgfs_rm_context()' just assumes it's the valid DAMON context directory
only if a file of the name exist.  As a result, invalid memory access
could happen as below.  Fix the bug by checking if the given input is for
a directory.  This check can filter out non-context inputs because
directories under 'damon/' debugfs directory can be created via only
'mk_contexts' file.

This bug has found by syzbot[1].

[1] https://lore.kernel.org/damon/000000000000ede3ac05ec4abf8e@google.com/

Link: https://lkml.kernel.org/r/20221107165001.5717-2-sj@kernel.org
Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: syzbot+6087eafb76a94c4ac9eb@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>	[5.15.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/damon/dbgfs.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/mm/damon/dbgfs.c~mm-damon-dbgfs-check-if-rm_contexts-input-is-for-a-real-context
+++ a/mm/damon/dbgfs.c
@@ -890,6 +890,7 @@ out:
 static int dbgfs_rm_context(char *name)
 {
 	struct dentry *root, *dir, **new_dirs;
+	struct inode *inode;
 	struct damon_ctx **new_ctxs;
 	int i, j;
 	int ret = 0;
@@ -905,6 +906,12 @@ static int dbgfs_rm_context(char *name)
 	if (!dir)
 		return -ENOENT;
 
+	inode = d_inode(dir);
+	if (!S_ISDIR(inode->i_mode)) {
+		ret = -EINVAL;
+		goto out_dput;
+	}
+
 	new_dirs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_dirs),
 			GFP_KERNEL);
 	if (!new_dirs) {
_

Patches currently in -mm which might be from sj@kernel.org are

mm-damon-core-split-out-damos-charged-region-skip-logic-into-a-new-function.patch
mm-damon-core-split-damos-application-logic-into-a-new-function.patch
mm-damon-core-split-out-scheme-stat-update-logic-into-a-new-function.patch
mm-damon-core-split-out-scheme-quota-adjustment-logic-into-a-new-function.patch
mm-damon-sysfs-use-damon_addr_range-for-regions-start-and-end-values.patch
mm-damon-sysfs-remove-parameters-of-damon_sysfs_region_alloc.patch
mm-damon-sysfs-move-sysfs_lock-to-common-module.patch
mm-damon-sysfs-move-unsigned-long-range-directory-to-common-module.patch
mm-damon-sysfs-split-out-kdamond-independent-schemes-stats-update-logic-into-a-new-function.patch
mm-damon-sysfs-split-out-schemes-directory-implementation-to-separate-file.patch
mm-damon-modules-deduplicate-init-steps-for-damon-context-setup.patch
mm-damon-reclaimlru_sort-remove-unnecessarily-included-headers.patch
mm-damon-reclaim-enable-and-disable-synchronously.patch
selftests-damon-add-tests-for-damon_reclaims-enabled-parameter.patch
mm-damon-lru_sort-enable-and-disable-synchronously.patch
selftests-damon-add-tests-for-damon_lru_sorts-enabled-parameter.patch
docs-admin-guide-mm-damon-usage-describe-the-rules-of-sysfs-region-directories.patch
docs-admin-guide-mm-damon-usage-fix-wrong-usage-example-of-init_regions-file.patch
mm-damon-core-add-a-callback-for-scheme-target-regions-check.patch
mm-damon-sysfs-schemes-implement-schemes-tried_regions-directory.patch
mm-damon-sysfs-schemes-implement-scheme-region-directory.patch
mm-damon-sysfs-implement-damos-tried-regions-update-command.patch
mm-damon-sysfs-schemes-implement-damos-tried-regions-clear-command.patch
tools-selftets-damon-sysfs-test-tried_regions-directory-existence.patch
docs-admin-guide-mm-damon-usage-document-schemes-s-tried_regions-sysfs-directory.patch
docs-abi-damon-document-schemes-s-tried_regions-sysfs-directory.patch
selftests-damon-test-non-context-inputs-to-rm_contexts-file.patch