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 --- fs/proc/cpuinfo.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 fs/proc/cpuinfo.c (limited to 'fs/proc/cpuinfo.c') diff --git a/fs/proc/cpuinfo.c b/fs/proc/cpuinfo.c new file mode 100644 index 000000000..f38bda5b8 --- /dev/null +++ b/fs/proc/cpuinfo.c @@ -0,0 +1,28 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include + +extern const struct seq_operations cpuinfo_op; + +static int cpuinfo_open(struct inode *inode, struct file *file) +{ + return seq_open(file, &cpuinfo_op); +} + +static const struct proc_ops cpuinfo_proc_ops = { + .proc_flags = PROC_ENTRY_PERMANENT, + .proc_open = cpuinfo_open, + .proc_read_iter = seq_read_iter, + .proc_lseek = seq_lseek, + .proc_release = seq_release, +}; + +static int __init proc_cpuinfo_init(void) +{ + proc_create("cpuinfo", 0, NULL, &cpuinfo_proc_ops); + return 0; +} +fs_initcall(proc_cpuinfo_init); -- cgit v1.3.1