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/xen-hypercalls.sh | 13 +++++++++++++ 1 file changed, 13 insertions(+) create mode 100755 scripts/xen-hypercalls.sh (limited to 'scripts/xen-hypercalls.sh') diff --git a/scripts/xen-hypercalls.sh b/scripts/xen-hypercalls.sh new file mode 100755 index 000000000..f18b00843 --- /dev/null +++ b/scripts/xen-hypercalls.sh @@ -0,0 +1,13 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +out="$1" +shift +in="$@" + +for i in $in; do + eval $CPP $LINUXINCLUDE -dD -imacros "$i" -x c /dev/null +done | \ +awk '$1 == "#define" && $2 ~ /__HYPERVISOR_[a-z][a-z_0-9]*/ { v[$3] = $2 } + END { print "/* auto-generated by scripts/xen-hypercall.sh */" + for (i in v) if (!(v[i] in v)) + print "HYPERCALL("substr(v[i], 14)")"}' | sort -u >$out -- cgit v1.3.1