| Message ID | 20220902125631.128329-1-gregkh@linuxfoundation.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/damon/dbgfs: fix memory leak when using debugfs_lookup() | expand |
On Fri, 2 Sep 2022 14:56:31 +0200 Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > 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, I assume. > --- a/mm/damon/dbgfs.c > +++ b/mm/damon/dbgfs.c > @@ -915,6 +915,7 @@ static int dbgfs_rm_context(char *name) > new_ctxs[j++] = dbgfs_ctxs[i]; > } > > + dput(dir); > kfree(dbgfs_dirs); > kfree(dbgfs_ctxs); > dput() is also needed if either of the kmalloc_array() calls fail? Maybe something like --- a/mm/damon/dbgfs.c~a +++ a/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; @@ -899,14 +900,12 @@ 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; + goto out_dput; new_ctxs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_ctxs), GFP_KERNEL); - if (!new_ctxs) { - kfree(new_dirs); - return -ENOMEM; - } + if (!new_ctxs) + goto out_new_dirs; for (i = 0, j = 0; i < dbgfs_nr_ctxs; i++) { if (dbgfs_dirs[i] == dir) { @@ -925,7 +924,13 @@ 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,
Hi Andrew and Greg! On Fri, 2 Sep 2022 09:17:03 -0700 Andrew Morton <akpm@linux-foundation.org> wrote: > On Fri, 2 Sep 2022 14:56:31 +0200 Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > > 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(). Thank you for finding this bug and posting this patch, Greg! > > > > ... > > > > Fixes: 75c1c2b53c78b, I assume. Correct, Andrew. Fixes: 75c1c2b53c78b ("mm/damon/dbgfs: support multiple contexts") Cc: <stable@vger.kernel.org> # 5.15.x > > > --- a/mm/damon/dbgfs.c > > +++ b/mm/damon/dbgfs.c > > @@ -915,6 +915,7 @@ static int dbgfs_rm_context(char *name) > > new_ctxs[j++] = dbgfs_ctxs[i]; > > } > > > > + dput(dir); > > kfree(dbgfs_dirs); > > kfree(dbgfs_ctxs); > > > > dput() is also needed if either of the kmalloc_array() calls fail? > Maybe something like Good catch. > > --- a/mm/damon/dbgfs.c~a > +++ a/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; > @@ -899,14 +900,12 @@ 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; > + goto out_dput; Shouldn't we also do 'ret = -ENOMEM;' before 'godo out_dput'? > > new_ctxs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_ctxs), > GFP_KERNEL); > - if (!new_ctxs) { > - kfree(new_dirs); > - return -ENOMEM; > - } > + if (!new_ctxs) > + goto out_new_dirs; ditto. > > for (i = 0, j = 0; i < dbgfs_nr_ctxs; i++) { > if (dbgfs_dirs[i] == dir) { > @@ -925,7 +924,13 @@ 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, > _ Thanks, SJ
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c index cb8a7e9926a4..dfb6ef8c83e0 100644 --- a/mm/damon/dbgfs.c +++ b/mm/damon/dbgfs.c @@ -915,6 +915,7 @@ static int dbgfs_rm_context(char *name) new_ctxs[j++] = dbgfs_ctxs[i]; } + dput(dir); kfree(dbgfs_dirs); kfree(dbgfs_ctxs);
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(). Cc: SeongJae Park <sj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: damon@lists.linux.dev Cc: linux-mm@kvack.org Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- mm/damon/dbgfs.c | 1 + 1 file changed, 1 insertion(+)