From: Chao Yu <yuchao0@xxxxxxxxxx> [ Upstream commit a8933b6b68f775b5774e7b075447fae13f4d01fe ] As reported in bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=204193 A null pointer dereference bug is triggered in f2fs under kernel-5.1.3. kasan_report.cold+0x5/0x32 f2fs_write_end_io+0x215/0x650 bio_endio+0x26e/0x320 blk_update_request+0x209/0x5d0 blk_mq_end_request+0x2e/0x230 lo_complete_rq+0x12c/0x190 blk_done_softirq+0x14a/0x1a0 __do_softirq+0x119/0x3e5 irq_exit+0x94/0xe0 call_function_single_interrupt+0xf/0x20 During umount, we will access NULL sbi->node_inode pointer in f2fs_write_end_io(): f2fs_bug_on(sbi, page->mapping == NODE_MAPPING(sbi) && page->index != nid_of_node(page)); The reason is if disable_checkpoint mount option is on, meta dirty pages can remain during umount, and then be flushed by iput() of meta_inode, however node_inode has been iput()ed before meta_inode's iput(). Since checkpoint is disabled, all meta/node datas are useless and should be dropped in next mount, so in umount, let's adjust drop_inode() to give a hint to iput_final() to drop all those dirty datas correctly. Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/f2fs/super.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 973f1e8187706..01038aff5d8e0 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -894,7 +894,21 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb) static int f2fs_drop_inode(struct inode *inode) { + struct f2fs_sb_info *sbi = F2FS_I_SB(inode); int ret; + + /* + * during filesystem shutdown, if checkpoint is disabled, + * drop useless meta/node dirty pages. + */ + if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) { + if (inode->i_ino == F2FS_NODE_INO(sbi) || + inode->i_ino == F2FS_META_INO(sbi)) { + trace_f2fs_drop_inode(inode, 1); + return 1; + } + } + /* * This is to avoid a deadlock condition like below. * writeback_single_inode(inode) -- 2.20.1
