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authorRyusuke Konishi <konishi.ryusuke@gmail.com>2022-10-04 00:05:19 +0900
committerAndrew Morton <akpm@linux-foundation.org>2022-10-11 19:05:44 -0700
commitd325dc6eb763c10f591c239550b8c7e5466a5d09 (patch)
tree6fc9482d6abf38a75889208b399196de59b8dafa /fs/nilfs2
parentb1f44cdabad8c50cd72d6b6731e9fdf3730a8f4f (diff)
nilfs2: fix use-after-free bug of struct nilfs_root
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. Link: https://lkml.kernel.org/r/20221003150519.39789-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com> Reported-by: syzbot+b8c672b0e22615c80fe0@syzkaller.appspotmail.com Reported-by: Khalid Masum <khalid.masum.92@gmail.com> Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'fs/nilfs2')
-rw-r--r--fs/nilfs2/inode.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index 67f63cfeade5..b074144f6f83 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -328,6 +328,7 @@ 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;
@@ -343,11 +344,25 @@ 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_warn(sb,
+ "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_info(sb, "repaired inode bitmap for reserved inodes");
+ }
+ ii->i_bh = bh;
+
atomic64_inc(&root->inodes_count);
inode_init_owner(&init_user_ns, inode, dir, mode);
inode->i_ino = ino;