From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall 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 Signed-off-by: Stafford Horne --- scripts/coccinelle/tests/doubletest.cocci | 59 +++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) create mode 100644 scripts/coccinelle/tests/doubletest.cocci (limited to 'scripts/coccinelle/tests/doubletest.cocci') diff --git a/scripts/coccinelle/tests/doubletest.cocci b/scripts/coccinelle/tests/doubletest.cocci new file mode 100644 index 000000000..c3d94c319 --- /dev/null +++ b/scripts/coccinelle/tests/doubletest.cocci @@ -0,0 +1,59 @@ +// SPDX-License-Identifier: GPL-2.0-only +/// Find &&/|| operations that include the same argument more than once +//# A common source of false positives is when the expression, or +//# another expresssion in the same && or || operation, performs a +//# side effect. +/// +// Confidence: Moderate +// Copyright: (C) 2010 Nicolas Palix, DIKU. +// Copyright: (C) 2010 Julia Lawall, DIKU. +// Copyright: (C) 2010 Gilles Muller, INRIA/LiP6. +// URL: https://coccinelle.gitlabpages.inria.fr/website +// Comments: +// Options: --no-includes --include-headers + +virtual context +virtual org +virtual report + +@r expression@ +expression E; +position p; +@@ + +( + E@p || ... || E +| + E@p && ... && E +) + +@bad@ +expression r.E,e1,e2,fn; +position r.p; +assignment operator op; +@@ + +( +E@p +& + <+... \(fn(...)\|e1 op e2\|e1++\|e1--\|++e1\|--e1\) ...+> +) + +@depends on context && !bad@ +expression r.E; +position r.p; +@@ + +*E@p + +@script:python depends on org && !bad@ +p << r.p; +@@ + +cocci.print_main("duplicated argument to && or ||",p) + +@script:python depends on report && !bad@ +p << r.p; +@@ + +coccilib.report.print_report(p[0],"duplicated argument to && or ||") -- cgit v1.3.1