mainline inclusion from mainline-v7.2-rc1 commit 10da12d352b7b2bb330a8609fdda9a58bf0e9856 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/18161 CVE: CVE-2026-74359 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- Normally ->s_dentry is cleared when dentry it's pointing to becomes negative (on eviction, realistically). However, that only happens if dentry gets to be positive in the first place; in case of inode allocation failure dentry never becomes positive, so ->d_iput() is not called at all. We do part of what normally would've been done by configfs_d_iput() (dropping the reference to configfs_dirent) manually, but we do not clear ->s_dentry there. Sloppy as it is, it does not matter in case of configfs_create_{dir,link}() - there configfs_dirent does not survive dropping the sole reference to it. However, for configfs_lookup() it *does* survive, with a dangling pointer to soon to be freed dentry sitting it its ->s_dentry. Subsequent getdents(2) in that directory will end up dereferencing that pointer in order to pick the inode number. Use after free... This is the minimal fix; the right approach is to set the linkage between dentry and configfs_dirent only after we know that we have an inode, but that takes more surgery and the bug had been there since 2006, so... Fixes: 3d0f89bb1694 ("configfs: Add permission and ownership to configfs objects") # 2.6.16-rc3 Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Breno Leitao <leitao@debian.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Ran Hongyun <ranhongyun1@huawei.com> --- fs/configfs/dir.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index 687735be3cd4..150441b0f5c5 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -476,6 +476,9 @@ static struct dentry * configfs_lookup(struct inode *dir, inode = configfs_create(dentry, mode); if (IS_ERR(inode)) { + spin_lock(&configfs_dirent_lock); + sd->s_dentry = NULL; + spin_unlock(&configfs_dirent_lock); configfs_put(sd); return ERR_CAST(inode); } -- 2.52.0