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| author | Al Viro <viro@zeniv.linux.org.uk> | 2025-06-01 14:23:52 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-09-09 18:58:19 +0200 |
| commit | 6482c3dccbfb8d20e2856ce67c75856859930b3f (patch) | |
| tree | 298dcd763966935aee0a906214faae82bde74864 /fs | |
| parent | b9290581d2ecf6794856f784d1b20f5464b4e22e (diff) | |
| download | linux-6482c3dccbfb8d20e2856ce67c75856859930b3f.tar.gz linux-6482c3dccbfb8d20e2856ce67c75856859930b3f.tar.bz2 linux-6482c3dccbfb8d20e2856ce67c75856859930b3f.zip | |
fs/fhandle.c: fix a race in call of has_locked_children()
commit 1f282cdc1d219c4a557f7009e81bc792820d9d9a upstream.
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>
[ Harshit: Resolved conflicts due to missing commit:
db04662e2f4f ("fs: allow detached mounts in clone_private_mount()") in
linux-6.12.y ]
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
| -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 962fda4fa246..c8519302f582 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2227,7 +2227,7 @@ 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; @@ -2241,6 +2241,16 @@ 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; +} + /** * clone_private_mount - create a private clone of a path * @path: path to clone @@ -2268,7 +2278,7 @@ struct vfsmount *clone_private_mount(const struct path *path) return ERR_PTR(-EPERM); } - if (has_locked_children(old_mnt, path->dentry)) + if (__has_locked_children(old_mnt, path->dentry)) goto invalid; new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); @@ -2762,7 +2772,7 @@ static struct mount *__do_loopback(struct path *old_path, int recurse) if (!check_mnt(old) && old_path->dentry->d_op != &ns_dentry_operations) return mnt; - if (!recurse && has_locked_children(old, old_path->dentry)) + if (!recurse && __has_locked_children(old, old_path->dentry)) return mnt; if (recurse) @@ -3152,7 +3162,7 @@ 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 */ |