2022-09-02 20:16:01

by SeongJae Park

Subject: [PATCH v2] mm/damon/dbgfs: fix memory leak when using

From: Greg Kroah-Hartman <[email protected]>

debugfs_lookup()
Date: Fri, 2 Sep 2022 14:56:31 +0200 [thread overview]
Message-ID: <[email protected]> (raw)

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time. Fix this up by properly
calling dput().

Fixes: 75c1c2b53c78b ("mm/damon/dbgfs: support multiple contexts")
Cc: <[email protected]> # 5.15.x
Cc: SeongJae Park <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: SeongJae Park <[email protected]>
---
Changes from v1
(https://lore.kernel.org/damon/[email protected]/)
- Call dput() for failure-return case (Andrew Morton)

mm/damon/dbgfs.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index 3b55a1b219b5..652a94deafe3 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -884,6 +884,7 @@ static int dbgfs_rm_context(char *name)
struct dentry *root, *dir, **new_dirs;
struct damon_ctx **new_ctxs;
int i, j;
+ int ret = 0;

if (damon_nr_running_ctxs())
return -EBUSY;
@@ -898,14 +899,16 @@ static int dbgfs_rm_context(char *name)

new_dirs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_dirs),
GFP_KERNEL);
- if (!new_dirs)
- return -ENOMEM;
+ if (!new_dirs) {
+ ret = -ENOMEM;
+ goto out_dput;
+ }

new_ctxs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_ctxs),
GFP_KERNEL);
if (!new_ctxs) {
- kfree(new_dirs);
- return -ENOMEM;
+ ret = -ENOMEM;
+ goto out_new_dirs;
}

for (i = 0, j = 0; i < dbgfs_nr_ctxs; i++) {
@@ -925,7 +928,13 @@ static int dbgfs_rm_context(char *name)
dbgfs_ctxs = new_ctxs;
dbgfs_nr_ctxs--;

- return 0;
+ goto out_dput;
+
+out_new_dirs:
+ kfree(new_dirs);
+out_dput:
+ dput(dir);
+ return ret;
}

static ssize_t dbgfs_rm_context_write(struct file *file,
--
2.25.1

2022-09-03 05:53:47

by Greg Kroah-Hartman

Subject: Re: [PATCH v2] mm/damon/dbgfs: fix memory leak when using

On Fri, Sep 02, 2022 at 07:11:49PM +0000, SeongJae Park wrote:
> From: Greg Kroah-Hartman <[email protected]>
>
> debugfs_lookup()
> Date: Fri, 2 Sep 2022 14:56:31 +0200 [thread overview]
> Message-ID: <[email protected]> (raw)
>
> When calling debugfs_lookup() the result must have dput() called on it,
> otherwise the memory will leak over time. Fix this up by properly
> calling dput().
>
> Fixes: 75c1c2b53c78b ("mm/damon/dbgfs: support multiple contexts")
> Cc: <[email protected]> # 5.15.x
> Cc: SeongJae Park <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Greg Kroah-Hartman <[email protected]>
> Signed-off-by: Andrew Morton <[email protected]>
> Signed-off-by: SeongJae Park <[email protected]>
> ---
> Changes from v1
> (https://lore.kernel.org/damon/[email protected]/)
> - Call dput() for failure-return case (Andrew Morton)

Thanks for fixing this up, I missed the other return error cases in my
rush to audit the whole tree at once.

This version looks great, and I see Andrew has taken it now into his
tree, thanks!

greg k-h