From 50e1f8d22199b557337b3d1ec8520e4c5aa5c76e Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Mon, 7 Jul 2014 09:39:32 +0800 Subject: [PATCH] f2fs: avoid to access NULL pointer in issue_flush_thread Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=75861 Denis 2014-05-10 11:28:59 UTC reported: "F2FS-fs (mmcblk0p28): mounting.. Unable to handle kernel NULL pointer dereference at virtual address 00000018 ... [] (_raw_spin_lock+0x3c/0x70) from [] (issue_flush_thread+0x50/0x17c) [] (issue_flush_thread+0x50/0x17c) from [] (kthread+0x98/0xa4) [] (kthread+0x98/0xa4) from [] (kernel_thread_exit+0x0/0x8)" This patch assign cmd_control_info in sm_info before issue_flush_thread is being created, so this make sure that issue flush thread will have no chance to access invalid info in fcc. Signed-off-by: Chao Yu Reviewed-by: Gu Zheng Signed-off-by: Jaegeuk Kim --- fs/f2fs/segment.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index b22d5a0652bb..d04613df710a 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -272,14 +272,15 @@ int create_flush_cmd_control(struct f2fs_sb_info *sbi) return -ENOMEM; spin_lock_init(&fcc->issue_lock); init_waitqueue_head(&fcc->flush_wait_queue); + sbi->sm_info->cmd_control_info = fcc; fcc->f2fs_issue_flush = kthread_run(issue_flush_thread, sbi, "f2fs_flush-%u:%u", MAJOR(dev), MINOR(dev)); if (IS_ERR(fcc->f2fs_issue_flush)) { err = PTR_ERR(fcc->f2fs_issue_flush); kfree(fcc); + sbi->sm_info->cmd_control_info = NULL; return err; } - sbi->sm_info->cmd_control_info = fcc; return err; }