[PATCH AUTOSEL 6.2 09/18] fs/ntfs3: Fix a possible null-pointer dereference in ni_clear()

Sasha Levin
2023-05-09T21:22:23Z

From: Jia-Ju Bai <baijiaju1990@gmail.com>

[ Upstream commit ec275bf9693d19cc0fdce8436f4c425ced86f6e7 ]

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 <baijiaju1990@gmail.com>
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 912eeb3d34717..9f3c4f6a2a343 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);
--
2.39.2