2021-10-11 05:37:05

by Dongliang Mu

Subject: [PATCH] fs: fix GPF in nilfs_mdt_destroy

In alloc_inode, inode_init_always could return -NOMEM if
security_inode_alloc fails. In its error handling, i_callback and
nilfs_free_inode will be called. However, because inode->i_private is
not initialized due to the failure of security_inode_alloc, the function
nilfs_is_metadata_file_inode can return true and nilfs_mdt_destroy will
be executed to lead to GPF bug.

Fix this bug by moving the assignment of inode->i_private before
security_inode_alloc.

BTW, this bug is triggered by fault injection in the syzkaller.

Signed-off-by: Dongliang Mu <[email protected]>
---
fs/inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/inode.c b/fs/inode.c
index ed0cab8a32db..f6fce84bf550 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -160,6 +160,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
inode->i_dir_seq = 0;
inode->i_rdev = 0;
inode->dirtied_when = 0;
+ inode->i_private = NULL;

#ifdef CONFIG_CGROUP_WRITEBACK
inode->i_wb_frn_winner = 0;
@@ -194,7 +195,6 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
lockdep_set_class_and_name(&mapping->invalidate_lock,
&sb->s_type->invalidate_lock_key,
"mapping.invalidate_lock");
- inode->i_private = NULL;
inode->i_mapping = mapping;
INIT_HLIST_HEAD(&inode->i_dentry); /* buggered by rcu freeing */
#ifdef CONFIG_FS_POSIX_ACL
--
2.25.1

2022-01-21 21:14:19

by Dongliang Mu

Subject: Re: [PATCH] fs: fix GPF in nilfs_mdt_destroy

On Mon, Oct 11, 2021 at 11:10 AM Dongliang Mu <[email protected]> wrote:
>
> In alloc_inode, inode_init_always could return -NOMEM if
> security_inode_alloc fails. In its error handling, i_callback and
> nilfs_free_inode will be called. However, because inode->i_private is
> not initialized due to the failure of security_inode_alloc, the function
> nilfs_is_metadata_file_inode can return true and nilfs_mdt_destroy will
> be executed to lead to GPF bug.
>
> Fix this bug by moving the assignment of inode->i_private before
> security_inode_alloc.
>

ping?

> BTW, this bug is triggered by fault injection in the syzkaller.
>
> Signed-off-by: Dongliang Mu <[email protected]>
> ---
> fs/inode.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index ed0cab8a32db..f6fce84bf550 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -160,6 +160,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
> inode->i_dir_seq = 0;
> inode->i_rdev = 0;
> inode->dirtied_when = 0;
> + inode->i_private = NULL;
>
> #ifdef CONFIG_CGROUP_WRITEBACK
> inode->i_wb_frn_winner = 0;
> @@ -194,7 +195,6 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
> lockdep_set_class_and_name(&mapping->invalidate_lock,
> &sb->s_type->invalidate_lock_key,
> "mapping.invalidate_lock");
> - inode->i_private = NULL;
> inode->i_mapping = mapping;
> INIT_HLIST_HEAD(&inode->i_dentry); /* buggered by rcu freeing */
> #ifdef CONFIG_FS_POSIX_ACL
> --
> 2.25.1
>