From: Baokun Li libaokun1@huawei.com

This is backport to 5.4 stable kernel. It fixes an issue reported by syzkaller.

commit f87c7a4b084afc13190cbb263538e444cb2b392a upstream

Hulk Robot reported a BUG_ON: ================================================================== EXT4-fs error (device loop3): ext4_mb_generate_buddy:805: group 0, block bitmap and bg descriptor inconsistent: 25 vs 31513 free clusters kernel BUG at fs/ext4/ext4_jbd2.c:53! invalid opcode: 0000 [#1] SMP KASAN PTI CPU: 0 PID: 25371 Comm: syz-executor.3 Not tainted 5.10.0+ #1 RIP: 0010:ext4_put_nojournal fs/ext4/ext4_jbd2.c:53 [inline] RIP: 0010:__ext4_journal_stop+0x10e/0x110 fs/ext4/ext4_jbd2.c:116 [...] Call Trace: ext4_write_inline_data_end+0x59a/0x730 fs/ext4/inline.c:795 generic_perform_write+0x279/0x3c0 mm/filemap.c:3344 ext4_buffered_write_iter+0x2e3/0x3d0 fs/ext4/file.c:270 ext4_file_write_iter+0x30a/0x11c0 fs/ext4/file.c:520 do_iter_readv_writev+0x339/0x3c0 fs/read_write.c:732 do_iter_write+0x107/0x430 fs/read_write.c:861 vfs_writev fs/read_write.c:934 [inline] do_pwritev+0x1e5/0x380 fs/read_write.c:1031 [...] ==================================================================

Above issue may happen as follows: cpu1 cpu2 __________________________|__________________________ do_pwritev vfs_writev do_iter_write ext4_file_write_iter ext4_buffered_write_iter generic_perform_write ext4_da_write_begin vfs_fallocate ext4_fallocate ext4_convert_inline_data ext4_convert_inline_data_nolock ext4_destroy_inline_data_nolock clear EXT4_STATE_MAY_INLINE_DATA ext4_map_blocks ext4_ext_map_blocks ext4_mb_new_blocks ext4_mb_regular_allocator ext4_mb_good_group_nolock ext4_mb_init_group ext4_mb_init_cache ext4_mb_generate_buddy --> error ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) ext4_restore_inline_data set EXT4_STATE_MAY_INLINE_DATA ext4_block_write_begin ext4_da_write_end ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) ext4_write_inline_data_end handle=NULL ext4_journal_stop(handle) __ext4_journal_stop ext4_put_nojournal(handle) ref_cnt = (unsigned long)handle BUG_ON(ref_cnt == 0) ---> BUG_ON

The lock held by ext4_convert_inline_data is xattr_sem, but the lock held by generic_perform_write is i_rwsem. Therefore, the two locks can be concurrent.

To solve above issue, we add inode_lock() for ext4_convert_inline_data(). At the same time, move ext4_convert_inline_data() in front of ext4_punch_hole(), remove similar handling from ext4_punch_hole().

Fixes: 0c8d414f163f ("ext4: let fallocate handle inline data correctly") Cc: stable@vger.kernel.org Reported-by: syzbot+2cc95c8e803bc7c9e5cb@syzkaller.appspotmail.com Reported-by: Hulk Robot hulkci@huawei.com Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Jan Kara jack@suse.cz Link: https://syzkaller.appspot.com/bug?id=184195865fd95e1e551f8af0fe43858126d1507... Link: https://lore.kernel.org/r/20220428134031.4153381-1-libaokun1@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Tadeusz Struk tadeusz.struk@linaro.org --- fs/ext4/extents.c | 8 +++++--- fs/ext4/inode.c | 9 --------- 2 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index f1bbce4350c4..d5e649e578cb 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4932,13 +4932,15 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len) FALLOC_FL_INSERT_RANGE)) return -EOPNOTSUPP;

- if (mode & FALLOC_FL_PUNCH_HOLE) - return ext4_punch_hole(inode, offset, len); - + inode_lock(inode); ret = ext4_convert_inline_data(inode); + inode_unlock(inode); if (ret) return ret;

+ if (mode & FALLOC_FL_PUNCH_HOLE) + return ext4_punch_hole(inode, offset, len); + if (mode & FALLOC_FL_COLLAPSE_RANGE) return ext4_collapse_range(inode, offset, len);

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 1cac574911a7..d8fee911d4f4 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4322,15 +4322,6 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)

trace_ext4_punch_hole(inode, offset, length, 0);

- ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA); - if (ext4_has_inline_data(inode)) { - down_write(&EXT4_I(inode)->i_mmap_sem); - ret = ext4_convert_inline_data(inode); - up_write(&EXT4_I(inode)->i_mmap_sem); - if (ret) - return ret; - } - /* * Write out all dirty pages to avoid race conditions * Then release them.