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, 56 insertions, 0 deletions

diff --git a/rust/zerocopy/rustdoc/style.css b/rust/zerocopy/rustdoc/style.css
new file mode 100644
index 000000000..d2d55ad2e
--- /dev/null
+++ b/rust/zerocopy/rustdoc/style.css
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT */
+/*
+Copyright 2026 The Fuchsia Authors
+
+Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0
+<LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
+license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
+This file may not be copied, modified, or distributed except according to
+those terms.
+*/
+
+.codegen-tabs {
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+    grid-template-columns: repeat(var(--arity), minmax(200px, 1fr));
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+}
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+.codegen-tabs:not(:has(> details[open]))::after {
+    grid-column: 1/-1;
+    content: 'Click one of the above headers to expand its contents.';
+    font-style: italic;
+    font-size: small;
+    text-align: center;
+}
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+.codegen-tabs details {
+    display: grid;
+    grid-column: 1 / -1;
+    grid-row: 1 / span 2;
+    grid-template-columns: subgrid;
+    grid-template-rows: subgrid;
+}
+
+.codegen-tabs summary {
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+    grid-column: var(--n) / span 1;
+    grid-row: 1;
+    z-index: 1;
+    border-bottom: 2px solid var(--headings-border-bottom-color);
+    cursor: pointer;
+}
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+.codegen-tabs details[open] > summary {
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+}
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+.codegen-tabs details::details-content {
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+}
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+.codegen-tabs details:not([open])::details-content {
+    display: none;
+}