lkml.org 
[lkml]   [2022]   [Aug]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.15 107/136] mm/damon/dbgfs: avoid duplicate context directory creation
Date
From: Badari Pulavarty <badari.pulavarty@intel.com>

commit d26f60703606ab425eee9882b32a1781a8bed74d upstream.

When user tries to create a DAMON context via the DAMON debugfs interface
with a name of an already existing context, the context directory creation
fails but a new context is created and added in the internal data
structure, due to absence of the directory creation success check. As a
result, memory could leak and DAMON cannot be turned on. An example test
case is as below:

# cd /sys/kernel/debug/damon/
# echo "off" > monitor_on
# echo paddr > target_ids
# echo "abc" > mk_context
# echo "abc" > mk_context
# echo $$ > abc/target_ids
# echo "on" > monitor_on <<< fails

Return value of 'debugfs_create_dir()' is expected to be ignored in
general, but this is an exceptional case as DAMON feature is depending
on the debugfs functionality and it has the potential duplicate name
issue. This commit therefore fixes the issue by checking the directory
creation failure and immediately return the error in the case.

Link: https://lkml.kernel.org/r/20220821180853.2400-1-sj@kernel.org
Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts")
Signed-off-by: Badari Pulavarty <badari.pulavarty@intel.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [ 5.15.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/damon/dbgfs.c | 3 +++
1 file changed, 3 insertions(+)

--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -376,6 +376,9 @@ static int dbgfs_mk_context(char *name)
return -ENOENT;

new_dir = debugfs_create_dir(name, root);
+ /* Below check is required for a potential duplicated name case */
+ if (IS_ERR(new_dir))
+ return PTR_ERR(new_dir);
dbgfs_dirs[dbgfs_nr_ctxs] = new_dir;

new_ctx = dbgfs_new_ctx();

\
 
 \ /
  Last update: 2022-08-29 13:23    [W:2.139 / U:1.412 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site