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Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

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Pull mount leak fix from Al Viro:
 "Regression fix for the syscalls-for-init series - fix a leak of a 'struct path'"

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs: fix a struct path leak in path_umount
This commit is contained in:
Linus Torvalds 2020-08-07 21:03:25 -07:00
commit d57b2b5bc4
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 #endif
int path_umount(struct path *path, int flags) static int can_umount(const struct path *path, int flags)
{ {
struct mount *mnt; struct mount *mnt = real_mount(path->mnt);
int retval;
if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
return -EINVAL; return -EINVAL;
if (!may_mount()) if (!may_mount())
return -EPERM; return -EPERM;
mnt = real_mount(path->mnt);
retval = -EINVAL;
if (path->dentry != path->mnt->mnt_root) if (path->dentry != path->mnt->mnt_root)
goto dput_and_out; return -EINVAL;
if (!check_mnt(mnt)) if (!check_mnt(mnt))
goto dput_and_out; return -EINVAL;
if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */ if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */
goto dput_and_out; return -EINVAL;
retval = -EPERM;
if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN)) 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 */ /* we mustn't call path_put() as that would clear mnt_expiry_mark */
dput(path->dentry); dput(path->dentry);
mntput_no_expire(mnt); mntput_no_expire(mnt);
return retval; return ret;
} }
static int ksys_umount(char __user *name, int flags) static int ksys_umount(char __user *name, int flags)