When vfs_mkdir() fails, the error code is not extracted from the
returned error pointer. This causes mkdir_error to be reached with
ret=0, which leads to returning ERR_PTR(0) (NULL) instead of a
proper error pointer.

Fix this by extracting the error code from the error pointer when
vfs_mkdir() fails.

Fixes: 406fad7698f5 ("cachefiles: Fix oops in vfs_mkdir from cachefiles_get_directory")
Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn>
---
 fs/cachefiles/namei.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 1b83ed0e0a63..2937db690b40 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -130,6 +130,8 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 		ret = cachefiles_inject_write_error();
 		if (ret == 0) {
 			subdir = vfs_mkdir(&nop_mnt_idmap, d_inode(dir), subdir, 0700, NULL);
+			if (IS_ERR(subdir))
+				ret = PTR_ERR(subdir);
 		} else {
 			end_creating(subdir);
 			subdir = ERR_PTR(ret);
-- 
2.25.1

On Wed, 13 May 2026 18:34:06 +0800, Hongling Zeng wrote:
> When vfs_mkdir() fails, the error code is not extracted from the
> returned error pointer. This causes mkdir_error to be reached with
> ret=0, which leads to returning ERR_PTR(0) (NULL) instead of a
> proper error pointer.
> 
> Fix this by extracting the error code from the error pointer when
> vfs_mkdir() fails.
> 
> [...]

Applied to the vfs.fixes branch of the vfs/vfs.git tree.
Patches in the vfs.fixes branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.fixes

[1/1] cachefiles: Fix error return when vfs_mkdir() fails
      https://git.kernel.org/vfs/vfs/c/8a220d1c312c