commit d325dc6eb763c10f591c239550b8c7e5466a5d09 upstream. If the beginning of the inode bitmap area is corrupted on disk, an inode with the same inode number as the root inode can be allocated and fail soon after. In this case, the subsequent call to nilfs_clear_inode() on that bogus root inode will wrongly decrement the reference counter of struct nilfs_root, and this will erroneously free struct nilfs_root, causing kernel oopses. This fixes the problem by changing nilfs_new_inode() to skip reserved inode numbers while repairing the inode bitmap. [ ryusuke: tweaked to use nilfs_msg macro instead of nilfs_warn and nilfs_info, which are not present in v5.8 and earlier. ] Link: https://lkml.kernel.org/r/20221003150519.39789-1-konishi.ryusuke@xxxxxxxxx Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx> Reported-by: syzbot+b8c672b0e22615c80fe0@xxxxxxxxxxxxxxxxxxxxxxxxx Reported-by: Khalid Masum <khalid.masum.92@xxxxxxxxx> Tested-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Please apply this patch to the above stable trees instead of the patch that could not be applied to them last time. This tweaked patch is applicable to v4.8~v5.8 and tested with the stable trees. fs/nilfs2/inode.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c index b8ebfb16c8ec..cf01aa55dd44 100644 --- a/fs/nilfs2/inode.c +++ b/fs/nilfs2/inode.c @@ -340,6 +340,7 @@ struct inode *nilfs_new_inode(struct inode *dir, umode_t mode) struct inode *inode; struct nilfs_inode_info *ii; struct nilfs_root *root; + struct buffer_head *bh; int err = -ENOMEM; ino_t ino; @@ -355,11 +356,26 @@ struct inode *nilfs_new_inode(struct inode *dir, umode_t mode) ii->i_state = BIT(NILFS_I_NEW); ii->i_root = root; - err = nilfs_ifile_create_inode(root->ifile, &ino, &ii->i_bh); + err = nilfs_ifile_create_inode(root->ifile, &ino, &bh); if (unlikely(err)) goto failed_ifile_create_inode; /* reference count of i_bh inherits from nilfs_mdt_read_block() */ + if (unlikely(ino < NILFS_USER_INO)) { + nilfs_msg(sb, KERN_WARNING, + "inode bitmap is inconsistent for reserved inodes"); + do { + brelse(bh); + err = nilfs_ifile_create_inode(root->ifile, &ino, &bh); + if (unlikely(err)) + goto failed_ifile_create_inode; + } while (ino < NILFS_USER_INO); + + nilfs_msg(sb, KERN_INFO, + "repaired inode bitmap for reserved inodes"); + } + ii->i_bh = bh; + atomic64_inc(&root->inodes_count); inode_init_owner(inode, dir, mode); inode->i_ino = ino; -- 2.31.1
