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();