From: Zhang Yi <yi.zhang@huawei.com> hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I476C7 CVE: NA --------------------------- In ext4_get_inode_loc(), we may skip IO and get an zero && uptodate inode buffer when the inode monopolize an inode block for performance reason. For most cases, ext4_mark_iloc_dirty() will fill the inode buffer to make it fine, but we could miss this call if something bad happened. Finally, __ext4_get_inode_loc_noinmem() may probably get an empty inode buffer and trigger ext4 error. For example, if we remove a nonexistent xattr on inode A, ext4_xattr_set_handle() will return ENODATA before invoking ext4_mark_iloc_dirty(), it will left an uptodate but zero buffer. We will get checksum error message in ext4_iget() when getting inode again. EXT4-fs error (device sda): ext4_lookup:1784: inode #131074: comm cat: iget: checksum invalid Even worse, if we allocate another inode B at the same inode block, it will corrupt the inode A on disk when write back inode B. So this patch postpone the initialization and mark buffer uptodate logic until shortly before we fill correct inode data in ext4_do_update_inode() if skip read I/O, ensure the buffer is really uptodate. Signed-off-by: Zhang Yi <yi.zhang@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Yang Erkun <yangerkun@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- fs/ext4/inode.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index a032f211b80cf..8251a1d62f164 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4677,9 +4677,12 @@ static int __ext4_get_inode_loc(struct inode *inode, } brelse(bitmap_bh); if (i == start + inodes_per_block) { - /* all other inodes are free, so skip I/O */ - memset(bh->b_data, 0, bh->b_size); - set_buffer_uptodate(bh); + /* + * All other inodes are free, skip I/O. Return + * uninitialized buffer immediately, initialization + * is postponed until shortly before we fill inode + * contents. + */ unlock_buffer(bh); goto has_buffer; } @@ -5281,6 +5284,24 @@ static int ext4_do_update_inode(handle_t *handle, gid_t i_gid; projid_t i_projid; + /* + * If the buffer is not uptodate, it means all information of the + * inode is in memory and we got this buffer without reading the + * block. We must be cautious that once we mark the buffer as + * uptodate, we rely on filling in the correct inode data later + * in this function. Otherwise if we left uptodate buffer without + * copying proper inode contents, we could corrupt the inode on + * disk after allocating another inode in the same block. + */ + if (!buffer_uptodate(bh)) { + lock_buffer(bh); + if (!buffer_uptodate(bh)) { + memset(bh->b_data, 0, bh->b_size); + set_buffer_uptodate(bh); + } + unlock_buffer(bh); + } + spin_lock(&ei->i_raw_lock); /* -- 2.25.1