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| author |   Al Viro <viro@zeniv.linux.org.uk> | 2025-06-01 14:23:52 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2025-06-07 00:37:38 -0400 |
| commit | 1f282cdc1d219c4a557f7009e81bc792820d9d9a (patch) | |
| tree | 06c228aaf056a1e93d2fb6f353bc780c8a06cbbe /fs/namespace.c | |
| parent | Merge tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs (diff) | |
| download | linux-rng-1f282cdc1d219c4a557f7009e81bc792820d9d9a.tar.xz linux-rng-1f282cdc1d219c4a557f7009e81bc792820d9d9a.zip | |
fs/fhandle.c: fix a race in call of has_locked_children()
may_decode_fh() is calling has_locked_children() while holding no locks.
That's an oopsable race...
The rest of the callers are safe since they are holding namespace_sem and
are guaranteed a positive refcount on the mount in question.
Rename the current has_locked_children() to __has_locked_children(), make
it static and switch the fs/namespace.c users to it.
Make has_locked_children() a wrapper for __has_locked_children(), calling
the latter under read_seqlock_excl(&mount_lock).
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Fixes: 620c266f3949 ("fhandle: relax open_by_handle_at() permission checks")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to '')
| -rw-r--r-- | fs/namespace.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 7c0ebc4f4ef2..a33553bc12d0 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2425,7 +2425,7 @@ void drop_collected_mounts(struct vfsmount *mnt) namespace_unlock(); } -bool has_locked_children(struct mount *mnt, struct dentry *dentry) +static bool __has_locked_children(struct mount *mnt, struct dentry *dentry) { struct mount *child; @@ -2439,6 +2439,16 @@ bool has_locked_children(struct mount *mnt, struct dentry *dentry) return false; } +bool has_locked_children(struct mount *mnt, struct dentry *dentry) +{ + bool res; + + read_seqlock_excl(&mount_lock); + res = __has_locked_children(mnt, dentry); + read_sequnlock_excl(&mount_lock); + return res; +} + /* * Check that there aren't references to earlier/same mount namespaces in the * specified subtree. Such references can act as pins for mount namespaces @@ -2499,7 +2509,7 @@ struct vfsmount *clone_private_mount(const struct path *path) return ERR_PTR(-EINVAL); } - if (has_locked_children(old_mnt, path->dentry)) + if (__has_locked_children(old_mnt, path->dentry)) return ERR_PTR(-EINVAL); new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); @@ -3036,7 +3046,7 @@ static struct mount *__do_loopback(struct path *old_path, int recurse) if (!may_copy_tree(old_path)) return mnt; - if (!recurse && has_locked_children(old, old_path->dentry)) + if (!recurse && __has_locked_children(old, old_path->dentry)) return mnt; if (recurse) @@ -3429,7 +3439,7 @@ static int do_set_group(struct path *from_path, struct path *to_path) goto out; /* From mount should not have locked children in place of To's root */ - if (has_locked_children(from, to->mnt.mnt_root)) + if (__has_locked_children(from, to->mnt.mnt_root)) goto out; /* Setting sharing groups is only allowed on private mounts */ |