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/misc/cstptr.cocci | 42 ++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 scripts/coccinelle/misc/cstptr.cocci (limited to 'scripts/coccinelle/misc/cstptr.cocci') diff --git a/scripts/coccinelle/misc/cstptr.cocci b/scripts/coccinelle/misc/cstptr.cocci new file mode 100644 index 000000000..74acf34be --- /dev/null +++ b/scripts/coccinelle/misc/cstptr.cocci @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0-only +/// PTR_ERR should be applied before its argument is reassigned, typically +/// to NULL +/// +// Confidence: High +// Copyright: (C) 2012 Julia Lawall, INRIA/LIP6. +// Copyright: (C) 2012 Gilles Muller, INRIA/LiP6. +// URL: https://coccinelle.gitlabpages.inria.fr/website +// Comments: +// Options: --no-includes --include-headers + +virtual org +virtual report +virtual context + +@r exists@ +expression e,e1; +constant c; +position p1,p2; +@@ + +*e@p1 = c +... when != e = e1 + when != &e + when != true IS_ERR(e) +*PTR_ERR@p2(e) + +@script:python depends on org@ +p1 << r.p1; +p2 << r.p2; +@@ + +cocci.print_main("PTR_ERR",p2) +cocci.print_secs("assignment",p1) + +@script:python depends on report@ +p1 << r.p1; +p2 << r.p2; +@@ + +msg = "ERROR: PTR_ERR applied after initialization to constant on line %s" % (p1[0].line) +coccilib.report.print_report(p2[0],msg) -- cgit v1.3.1