f2fs_fill_super
-> f2fs_build_segment_manager
-> create_discard_cmd_control
-> f2fs_start_discard_thread
It invokes kthread_run to create a thread and run issue_discard_thread.
However, if f2fs_build_node_manager fails, the control flow goes to
free_nm and calls f2fs_destroy_node_manager. This function will free
sbi->nm_info. However, if issue_discard_thread accesses sbi->nm_info
after the deallocation, but before the f2fs_stop_discard_thread, it will
cause UAF(Use-after-free).
-> f2fs_destroy_segment_manager
-> destroy_discard_cmd_control
-> f2fs_stop_discard_thread
Fix this by switching the order of f2fs_build_segment_manager
and f2fs_build_node_manager.
Signed-off-by: Dongliang Mu <mudonglianga...@gmail.com>
---
fs/f2fs/super.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 78ebc306ee2b..1a23b64cfb74 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -4135,18 +4135,18 @@ static int f2fs_fill_super(struct super_block *sb, void
*data, int silent)
}
/* setup f2fs internal modules */
- err = f2fs_build_segment_manager(sbi);
- if (err) {
- f2fs_err(sbi, "Failed to initialize F2FS segment manager (%d)",
- err);
- goto free_sm;
- }
err = f2fs_build_node_manager(sbi);
if (err) {
f2fs_err(sbi, "Failed to initialize F2FS node manager (%d)",
err);
goto free_nm;
}
+ err = f2fs_build_segment_manager(sbi);
+ if (err) {
+ f2fs_err(sbi, "Failed to initialize F2FS segment manager (%d)",
+ err);
+ goto free_sm;
+ }
/* For write statistics */
sbi->sectors_written_start = f2fs_get_sectors_written(sbi);
@@ -4351,10 +4351,10 @@ static int f2fs_fill_super(struct super_block *sb, void
*data, int silent)
sbi->node_inode = NULL;
free_stats:
f2fs_destroy_stats(sbi);
-free_nm:
- f2fs_destroy_node_manager(sbi);
free_sm:
f2fs_destroy_segment_manager(sbi);
+free_nm:
+ f2fs_destroy_node_manager(sbi);
f2fs_destroy_post_read_wq(sbi);
stop_ckpt_thread:
f2fs_stop_ckpt_thread(sbi);
--
2.25.1
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