f2fs: fix potential use-after-free issue

In error path of f2fs_read_multi_pages(), it should let last referrer
release decompress io context memory, otherwise, other referrer will
cause use-after-free issue.

Fixes: 4c8ff7095bef ("f2fs: support data compression")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 8607c02..4d871d2 100644 (file)
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2208,16 +2208,16 @@ submit_and_realloc:
                                        page->index, for_write);
                        if (IS_ERR(bio)) {
                                ret = PTR_ERR(bio);
-                               bio = NULL;
                                dic->failed = true;
                                if (refcount_sub_and_test(dic->nr_cpages - i,
-                                                       &dic->ref))
+                                                       &dic->ref)) {
                                        f2fs_decompress_end_io(dic->rpages,
                                                        cc->cluster_size, true,
                                                        false);
-                               f2fs_free_dic(dic);
+                                       f2fs_free_dic(dic);
+                               }
                                f2fs_put_dnode(&dn);
-                               *bio_ret = bio;
+                               *bio_ret = NULL;
                                return ret;
                        }
                }