| Message ID | 20220102112141.12281-1-sj@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [for-v5.15.x] mm/damon/dbgfs: fix 'struct pid' leaks in 'dbgfs_target_ids_write()' | expand |
On Sun, Jan 02, 2022 at 11:21:41AM +0000, SeongJae Park wrote: > commit ebb3f994dd92f8fb4d70c7541091216c1e10cb71 upstream. > > DAMON debugfs interface increases the reference counts of 'struct pid's > for targets from the 'target_ids' file write callback > ('dbgfs_target_ids_write()'), but decreases the counts only in DAMON > monitoring termination callback ('dbgfs_before_terminate()'). > > Therefore, when 'target_ids' file is repeatedly written without DAMON > monitoring start/termination, the reference count is not decreased and > therefore memory for the 'struct pid' cannot be freed. This commit > fixes this issue by decreasing the reference counts when 'target_ids' is > written. > > Link: https://lkml.kernel.org/r/20211229124029.23348-1-sj@kernel.org > Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface") > 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: Linus Torvalds <torvalds@linux-foundation.org> > --- > This is a backport of a DAMON fix that merged in the mainline, for > v5.15.x stable series. Now queued up, thanks. greg k-h
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c index d3bc110430f9..36624990b577 100644 --- a/mm/damon/dbgfs.c +++ b/mm/damon/dbgfs.c @@ -185,6 +185,7 @@ static ssize_t dbgfs_target_ids_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { struct damon_ctx *ctx = file->private_data; + struct damon_target *t, *next_t; char *kbuf, *nrs; unsigned long *targets; ssize_t nr_targets; @@ -224,6 +225,13 @@ static ssize_t dbgfs_target_ids_write(struct file *file, goto unlock_out; } + /* remove previously set targets */ + damon_for_each_target_safe(t, next_t, ctx) { + if (targetid_is_pid(ctx)) + put_pid((struct pid *)t->id); + damon_destroy_target(t); + } + err = damon_set_targets(ctx, targets, nr_targets); if (err) { if (targetid_is_pid(ctx))
commit ebb3f994dd92f8fb4d70c7541091216c1e10cb71 upstream. DAMON debugfs interface increases the reference counts of 'struct pid's for targets from the 'target_ids' file write callback ('dbgfs_target_ids_write()'), but decreases the counts only in DAMON monitoring termination callback ('dbgfs_before_terminate()'). Therefore, when 'target_ids' file is repeatedly written without DAMON monitoring start/termination, the reference count is not decreased and therefore memory for the 'struct pid' cannot be freed. This commit fixes this issue by decreasing the reference counts when 'target_ids' is written. Link: https://lkml.kernel.org/r/20211229124029.23348-1-sj@kernel.org Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface") 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: Linus Torvalds <torvalds@linux-foundation.org> --- This is a backport of a DAMON fix that merged in the mainline, for v5.15.x stable series. mm/damon/dbgfs.c | 8 ++++++++ 1 file changed, 8 insertions(+)