Re: [syzbot] BUG: sleeping function called from invalid context in ntfs_d_hash

syzbot
2024-09-02T16:43:44Z

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Subject: BUG: sleeping function called from invalid context in ntfs_d_hash
Author: djahchankoike@gmail.com

#syz test

d_hash is done while under "rcu-walk" and should not sleep,
__get_name() allocates using GFP_KERNEL, having the possibility
to sleep when under memory pressure. Change the allocation to
GFP_NOWAIT.

Signed-off-by: Diogo Jahchan Koike <djahchankoike@gmail.com>
---
fs/ntfs3/namei.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/ntfs3/namei.c b/fs/ntfs3/namei.c
index f16d318c4372..d3d93651baa5 100644
--- a/fs/ntfs3/namei.c
+++ b/fs/ntfs3/namei.c
@@ -231,6 +231,7 @@ static int ntfs_rmdir(struct inode *dir, struct dentry *dentry)
/*
* ntfs_rename - inode_operations::rename
*/
+
static int ntfs_rename(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, struct inode *new_dir,
struct dentry *new_dentry, u32 flags)
@@ -395,7 +396,7 @@ static int ntfs_d_hash(const struct dentry *dentry, struct qstr *name)
/*
* Try slow way with current upcase table
*/
- uni = __getname();
+ uni = kmem_cache_alloc(names_cachep, GFP_NOWAIT);
if (!uni)
return -ENOMEM;

@@ -417,7 +418,7 @@ static int ntfs_d_hash(const struct dentry *dentry, struct qstr *name)
err = 0;

out:
- __putname(uni);
+ kmem_cache_free(names_cachep, uni);
return err;
}

--
2.43.0