Revision - 471f0aa - x86/fpu: Fix copy_xstate_to_uabi() to copy init states correctly

Revision 471f0aa7fa64e23766a1473b32d9ec3f0718895a authored by Chang S. Bae on 21 October 2022, 18:58:44 UTC, committed by Dave Hansen on 21 October 2022, 22:22:09 UTC

x86/fpu: Fix copy_xstate_to_uabi() to copy init states correctly

When an extended state component is not present in fpstate, but in init
state, the function copies from init_fpstate via copy_feature().

But, dynamic states are not present in init_fpstate because of all-zeros
init states. Then retrieving them from init_fpstate will explode like this:

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 ...
 RIP: 0010:memcpy_erms+0x6/0x10
  ? __copy_xstate_to_uabi_buf+0x381/0x870
  fpu_copy_guest_fpstate_to_uabi+0x28/0x80
  kvm_arch_vcpu_ioctl+0x14c/0x1460 [kvm]
  ? __this_cpu_preempt_check+0x13/0x20
  ? vmx_vcpu_put+0x2e/0x260 [kvm_intel]
  kvm_vcpu_ioctl+0xea/0x6b0 [kvm]
  ? kvm_vcpu_ioctl+0xea/0x6b0 [kvm]
  ? __fget_light+0xd4/0x130
  __x64_sys_ioctl+0xe3/0x910
  ? debug_smp_processor_id+0x17/0x20
  ? fpregs_assert_state_consistent+0x27/0x50
  do_syscall_64+0x3f/0x90
  entry_SYSCALL_64_after_hwframe+0x63/0xcd

Adjust the 'mask' to zero out the userspace buffer for the features that
are not available both from fpstate and from init_fpstate.

The dynamic features depend on the compacted XSAVE format. Ensure it is
enabled before reading XCOMP_BV in init_fpstate.

Fixes: 2308ee57d93d ("x86/fpu/amx: Enable the AMX feature in 64-bit mode")
Reported-by: Yuan Yao <yuan.yao@intel.com>
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Yuan Yao <yuan.yao@intel.com>
Link: https://lore.kernel.org/lkml/BYAPR11MB3717EDEF2351C958F2C86EED95259@BYAPR11MB3717.namprd11.prod.outlook.com/
Link: https://lkml.kernel.org/r/20221021185844.13472-1-chang.seok.bae@intel.com

1 parent b329f5d

Files
Changes

Permalinks

fs.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/io_uring.h>

#include <uapi/linux/io_uring.h>

#include "../fs/internal.h"

#include "io_uring.h"
#include "fs.h"

struct io_rename {
	struct file			*file;
	int				old_dfd;
	int				new_dfd;
	struct filename			*oldpath;
	struct filename			*newpath;
	int				flags;
};

struct io_unlink {
	struct file			*file;
	int				dfd;
	int				flags;
	struct filename			*filename;
};

struct io_mkdir {
	struct file			*file;
	int				dfd;
	umode_t				mode;
	struct filename			*filename;
};

struct io_link {
	struct file			*file;
	int				old_dfd;
	int				new_dfd;
	struct filename			*oldpath;
	struct filename			*newpath;
	int				flags;
};

int io_renameat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_rename *ren = io_kiocb_to_cmd(req, struct io_rename);
	const char __user *oldf, *newf;

	if (sqe->buf_index || sqe->splice_fd_in)
		return -EINVAL;
	if (unlikely(req->flags & REQ_F_FIXED_FILE))
		return -EBADF;

	ren->old_dfd = READ_ONCE(sqe->fd);
	oldf = u64_to_user_ptr(READ_ONCE(sqe->addr));
	newf = u64_to_user_ptr(READ_ONCE(sqe->addr2));
	ren->new_dfd = READ_ONCE(sqe->len);
	ren->flags = READ_ONCE(sqe->rename_flags);

	ren->oldpath = getname(oldf);
	if (IS_ERR(ren->oldpath))
		return PTR_ERR(ren->oldpath);

	ren->newpath = getname(newf);
	if (IS_ERR(ren->newpath)) {
		putname(ren->oldpath);
		return PTR_ERR(ren->newpath);
	}

	req->flags |= REQ_F_NEED_CLEANUP;
	return 0;
}

int io_renameat(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_rename *ren = io_kiocb_to_cmd(req, struct io_rename);
	int ret;

	if (issue_flags & IO_URING_F_NONBLOCK)
		return -EAGAIN;

	ret = do_renameat2(ren->old_dfd, ren->oldpath, ren->new_dfd,
				ren->newpath, ren->flags);

	req->flags &= ~REQ_F_NEED_CLEANUP;
	io_req_set_res(req, ret, 0);
	return IOU_OK;
}

void io_renameat_cleanup(struct io_kiocb *req)
{
	struct io_rename *ren = io_kiocb_to_cmd(req, struct io_rename);

	putname(ren->oldpath);
	putname(ren->newpath);
}

int io_unlinkat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_unlink *un = io_kiocb_to_cmd(req, struct io_unlink);
	const char __user *fname;

	if (sqe->off || sqe->len || sqe->buf_index || sqe->splice_fd_in)
		return -EINVAL;
	if (unlikely(req->flags & REQ_F_FIXED_FILE))
		return -EBADF;

	un->dfd = READ_ONCE(sqe->fd);

	un->flags = READ_ONCE(sqe->unlink_flags);
	if (un->flags & ~AT_REMOVEDIR)
		return -EINVAL;

	fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
	un->filename = getname(fname);
	if (IS_ERR(un->filename))
		return PTR_ERR(un->filename);

	req->flags |= REQ_F_NEED_CLEANUP;
	return 0;
}

int io_unlinkat(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_unlink *un = io_kiocb_to_cmd(req, struct io_unlink);
	int ret;

	if (issue_flags & IO_URING_F_NONBLOCK)
		return -EAGAIN;

	if (un->flags & AT_REMOVEDIR)
		ret = do_rmdir(un->dfd, un->filename);
	else
		ret = do_unlinkat(un->dfd, un->filename);

	req->flags &= ~REQ_F_NEED_CLEANUP;
	io_req_set_res(req, ret, 0);
	return IOU_OK;
}

void io_unlinkat_cleanup(struct io_kiocb *req)
{
	struct io_unlink *ul = io_kiocb_to_cmd(req, struct io_unlink);

	putname(ul->filename);
}

int io_mkdirat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_mkdir *mkd = io_kiocb_to_cmd(req, struct io_mkdir);
	const char __user *fname;

	if (sqe->off || sqe->rw_flags || sqe->buf_index || sqe->splice_fd_in)
		return -EINVAL;
	if (unlikely(req->flags & REQ_F_FIXED_FILE))
		return -EBADF;

	mkd->dfd = READ_ONCE(sqe->fd);
	mkd->mode = READ_ONCE(sqe->len);

	fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
	mkd->filename = getname(fname);
	if (IS_ERR(mkd->filename))
		return PTR_ERR(mkd->filename);

	req->flags |= REQ_F_NEED_CLEANUP;
	return 0;
}

int io_mkdirat(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_mkdir *mkd = io_kiocb_to_cmd(req, struct io_mkdir);
	int ret;

	if (issue_flags & IO_URING_F_NONBLOCK)
		return -EAGAIN;

	ret = do_mkdirat(mkd->dfd, mkd->filename, mkd->mode);

	req->flags &= ~REQ_F_NEED_CLEANUP;
	io_req_set_res(req, ret, 0);
	return IOU_OK;
}

void io_mkdirat_cleanup(struct io_kiocb *req)
{
	struct io_mkdir *md = io_kiocb_to_cmd(req, struct io_mkdir);

	putname(md->filename);
}

int io_symlinkat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_link *sl = io_kiocb_to_cmd(req, struct io_link);
	const char __user *oldpath, *newpath;

	if (sqe->len || sqe->rw_flags || sqe->buf_index || sqe->splice_fd_in)
		return -EINVAL;
	if (unlikely(req->flags & REQ_F_FIXED_FILE))
		return -EBADF;

	sl->new_dfd = READ_ONCE(sqe->fd);
	oldpath = u64_to_user_ptr(READ_ONCE(sqe->addr));
	newpath = u64_to_user_ptr(READ_ONCE(sqe->addr2));

	sl->oldpath = getname(oldpath);
	if (IS_ERR(sl->oldpath))
		return PTR_ERR(sl->oldpath);

	sl->newpath = getname(newpath);
	if (IS_ERR(sl->newpath)) {
		putname(sl->oldpath);
		return PTR_ERR(sl->newpath);
	}

	req->flags |= REQ_F_NEED_CLEANUP;
	return 0;
}

int io_symlinkat(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_link *sl = io_kiocb_to_cmd(req, struct io_link);
	int ret;

	if (issue_flags & IO_URING_F_NONBLOCK)
		return -EAGAIN;

	ret = do_symlinkat(sl->oldpath, sl->new_dfd, sl->newpath);

	req->flags &= ~REQ_F_NEED_CLEANUP;
	io_req_set_res(req, ret, 0);
	return IOU_OK;
}

int io_linkat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_link *lnk = io_kiocb_to_cmd(req, struct io_link);
	const char __user *oldf, *newf;

	if (sqe->rw_flags || sqe->buf_index || sqe->splice_fd_in)
		return -EINVAL;
	if (unlikely(req->flags & REQ_F_FIXED_FILE))
		return -EBADF;

	lnk->old_dfd = READ_ONCE(sqe->fd);
	lnk->new_dfd = READ_ONCE(sqe->len);
	oldf = u64_to_user_ptr(READ_ONCE(sqe->addr));
	newf = u64_to_user_ptr(READ_ONCE(sqe->addr2));
	lnk->flags = READ_ONCE(sqe->hardlink_flags);

	lnk->oldpath = getname(oldf);
	if (IS_ERR(lnk->oldpath))
		return PTR_ERR(lnk->oldpath);

	lnk->newpath = getname(newf);
	if (IS_ERR(lnk->newpath)) {
		putname(lnk->oldpath);
		return PTR_ERR(lnk->newpath);
	}

	req->flags |= REQ_F_NEED_CLEANUP;
	return 0;
}

int io_linkat(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_link *lnk = io_kiocb_to_cmd(req, struct io_link);
	int ret;

	if (issue_flags & IO_URING_F_NONBLOCK)
		return -EAGAIN;

	ret = do_linkat(lnk->old_dfd, lnk->oldpath, lnk->new_dfd,
				lnk->newpath, lnk->flags);

	req->flags &= ~REQ_F_NEED_CLEANUP;
	io_req_set_res(req, ret, 0);
	return IOU_OK;
}

void io_link_cleanup(struct io_kiocb *req)
{
	struct io_link *sl = io_kiocb_to_cmd(req, struct io_link);

	putname(sl->oldpath);
	putname(sl->newpath);
}

Showing with 0 additions and 0 deletions (0 / 0 diffs computed)

Computing file changes ...