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fs: fix a struct path leak in path_umount

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Make sure we also put the dentry and vfsmnt in the illegal flags
and !may_umount cases.

Fixes: 41525f56e2 ("fs: refactor ksys_umount")
Reported-by: Vikas Kumar <vikas.kumar2@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig 2020-08-06 16:07:10 +02:00 committed by Al Viro
parent f073531070
commit 25ccd24ffd
1 changed files with 18 additions and 14 deletions
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32
fs/namespace.c
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@ -1706,34 +1706,38 @@ static inline bool may_mandlock(void)
}
#endif
int path_umount(struct path *path, int flags)
static int can_umount(const struct path *path, int flags)
{
struct mount *mnt;
int retval;
struct mount *mnt = real_mount(path->mnt);
if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
return -EINVAL;
if (!may_mount())
return -EPERM;
mnt = real_mount(path->mnt);
retval = -EINVAL;
if (path->dentry != path->mnt->mnt_root)
goto dput_and_out;
return -EINVAL;
if (!check_mnt(mnt))
goto dput_and_out;
return -EINVAL;
if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */
goto dput_and_out;
retval = -EPERM;
return -EINVAL;
if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
goto dput_and_out;
return -EPERM;
return 0;
}
int path_umount(struct path *path, int flags)
{
struct mount *mnt = real_mount(path->mnt);
int ret;
ret = can_umount(path, flags);
if (!ret)
ret = do_umount(mnt, flags);
retval = do_umount(mnt, flags);
dput_and_out:
/* we mustn't call path_put() as that would clear mnt_expiry_mark */
dput(path->dentry);
mntput_no_expire(mnt);
return retval;
return ret;
}
static int ksys_umount(char __user *name, int flags)