From: Dongliang Mu mudongliangabcd@gmail.com
commit 5429c9dbc9025f9a166f64e22e3a69c94fd5b29b upstream.
if2fs_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 stopping discard thread before f2fs_destroy_node_manager.
Note that, the commit d6d2b491a82e1 introduces the call of f2fs_available_free_memory into issue_discard_thread.
Cc: stable@vger.kernel.org Fixes: d6d2b491a82e ("f2fs: allow to change discard policy based on cached discard cmds") Signed-off-by: Dongliang Mu mudongliangabcd@gmail.com Reviewed-by: Chao Yu chao@kernel.org Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/f2fs/super.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -4271,6 +4271,8 @@ free_node_inode: free_stats: f2fs_destroy_stats(sbi); free_nm: + /* stop discard thread before destroying node manager */ + f2fs_stop_discard_thread(sbi); f2fs_destroy_node_manager(sbi); free_sm: f2fs_destroy_segment_manager(sbi);