openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 80 insertions, 0 deletions

diff --git a/fs/xfs/xfs_rtalloc.h b/fs/xfs/xfs_rtalloc.h
new file mode 100644
index 000000000..78a690b48
--- /dev/null
+++ b/fs/xfs/xfs_rtalloc.h
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ */
+#ifndef __XFS_RTALLOC_H__
+#define	__XFS_RTALLOC_H__
+
+/* kernel only definitions and functions */
+
+struct xfs_mount;
+struct xfs_trans;
+
+#ifdef CONFIG_XFS_RT
+/* rtgroup superblock initialization */
+int xfs_rtmount_readsb(struct xfs_mount *mp);
+void xfs_rtmount_freesb(struct xfs_mount *mp);
+
+/*
+ * Initialize realtime fields in the mount structure.
+ */
+int					/* error */
+xfs_rtmount_init(
+	struct xfs_mount	*mp);	/* file system mount structure */
+void
+xfs_rtunmount_inodes(
+	struct xfs_mount	*mp);
+
+/*
+ * Get the bitmap and summary inodes into the mount structure
+ * at mount time.
+ */
+int					/* error */
+xfs_rtmount_inodes(
+	struct xfs_mount	*mp);	/* file system mount structure */
+
+/*
+ * Grow the realtime area of the filesystem.
+ */
+int
+xfs_growfs_rt(
+	struct xfs_mount	*mp,	/* file system mount structure */
+	xfs_growfs_rt_t		*in);	/* user supplied growfs struct */
+
+int xfs_rtalloc_reinit_frextents(struct xfs_mount *mp);
+int xfs_growfs_check_rtgeom(const struct xfs_mount *mp, xfs_rfsblock_t dblocks,
+		xfs_rfsblock_t rblocks, xfs_agblock_t rextsize);
+#else
+# define xfs_growfs_rt(mp,in)				(-ENOSYS)
+# define xfs_rtalloc_reinit_frextents(m)		(0)
+# define xfs_rtmount_readsb(mp)				(0)
+# define xfs_rtmount_freesb(mp)				((void)0)
+static inline int		/* error */
+xfs_rtmount_init(
+	xfs_mount_t	*mp)	/* file system mount structure */
+{
+	if (mp->m_sb.sb_rblocks == 0)
+		return 0;
+
+	xfs_warn(mp, "Not built with CONFIG_XFS_RT");
+	return -ENOSYS;
+}
+# define xfs_rtmount_inodes(m)  (((mp)->m_sb.sb_rblocks == 0)? 0 : (-ENOSYS))
+# define xfs_rtunmount_inodes(m)
+
+static inline int
+xfs_growfs_check_rtgeom(const struct xfs_mount *mp,
+		xfs_rfsblock_t dblocks, xfs_rfsblock_t rblocks,
+		xfs_extlen_t rextsize)
+{
+	return 0;
+}
+#endif	/* CONFIG_XFS_RT */
+
+int xfs_rtallocate_rtgs(struct xfs_trans *tp, xfs_fsblock_t bno_hint,
+		xfs_rtxlen_t minlen, xfs_rtxlen_t maxlen, xfs_rtxlen_t prod,
+		bool wasdel, bool initial_user_data, xfs_rtblock_t *bno,
+		xfs_extlen_t *blen);
+
+#endif	/* __XFS_RTALLOC_H__ */