Messages in this thread Patch in this message | | | Date | Fri, 2 Sep 2022 09:17:03 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] mm/damon/dbgfs: fix memory leak when using debugfs_lookup() |
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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, _
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