2023-01-11 09:16:11

by Jia-Ju Bai

Subject: [PATCH] fs: ntfs3: Fix a possible null-pointer dereference in ni_clear()

In a previous commit c1006bd13146, ni->mi.mrec in ni_write_inode()
could be NULL, and thus a NULL check is added for this variable.

However, in the same call stack, ni->mi.mrec can be also dereferenced
in ni_clear():

ntfs_evict_inode(inode)
ni_write_inode(inode, ...)
ni = ntfs_i(inode);
is_rec_inuse(ni->mi.mrec) -> Add a NULL check by previous commit
ni_clear(ntfs_i(inode))
is_rec_inuse(ni->mi.mrec) -> No check

Thus, a possible null-pointer dereference may exist in ni_clear().
To fix it, a NULL check is added in this function.

Signed-off-by: Jia-Ju Bai <[email protected]>
Reported-by: TOTE Robot <[email protected]>
---
fs/ntfs3/frecord.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ntfs3/frecord.c b/fs/ntfs3/frecord.c
index f1df52dfab74..046ec4179d75 100644
--- a/fs/ntfs3/frecord.c
+++ b/fs/ntfs3/frecord.c
@@ -102,7 +102,7 @@ void ni_clear(struct ntfs_inode *ni)
{
struct rb_node *node;

- if (!ni->vfs_inode.i_nlink && is_rec_inuse(ni->mi.mrec))
+ if (!ni->vfs_inode.i_nlink && ni->mi.mrec && is_rec_inuse(ni->mi.mrec))
ni_delete_all(ni);

al_destroy(ni);
--
2.34.1

2023-05-08 13:03:55

by Konstantin Komarov

Subject: Re: [PATCH] fs: ntfs3: Fix a possible null-pointer dereference in ni_clear()

In a previous commit c1006bd13146, ni->mi.mrec in ni_write_inode()
> could be NULL, and thus a NULL check is added for this variable.
>
> However, in the same call stack, ni->mi.mrec can be also dereferenced
> in ni_clear():
>
> ntfs_evict_inode(inode)
> ni_write_inode(inode, ...)
> ni = ntfs_i(inode);
> is_rec_inuse(ni->mi.mrec) -> Add a NULL check by previous commit
> ni_clear(ntfs_i(inode))
> is_rec_inuse(ni->mi.mrec) -> No check
>
> Thus, a possible null-pointer dereference may exist in ni_clear().
> To fix it, a NULL check is added in this function.
>
> Signed-off-by: Jia-Ju Bai <[email protected]>
> Reported-by: TOTE Robot <[email protected]>
> ---
> fs/ntfs3/frecord.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ntfs3/frecord.c b/fs/ntfs3/frecord.c
> index f1df52dfab74..046ec4179d75 100644
> --- a/fs/ntfs3/frecord.c
> +++ b/fs/ntfs3/frecord.c
> @@ -102,7 +102,7 @@ void ni_clear(struct ntfs_inode *ni)
> {
> struct rb_node *node;
>
> - if (!ni->vfs_inode.i_nlink && is_rec_inuse(ni->mi.mrec))
> + if (!ni->vfs_inode.i_nlink && ni->mi.mrec && is_rec_inuse(ni->mi.mrec))
> ni_delete_all(ni);
>
> al_destroy(ni);

I apologize for the delayed response.

Thank you for your work, applied!