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 --- drivers/video/fbdev/i740fb.c | 1316 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 1316 insertions(+) create mode 100644 drivers/video/fbdev/i740fb.c (limited to 'drivers/video/fbdev/i740fb.c') diff --git a/drivers/video/fbdev/i740fb.c b/drivers/video/fbdev/i740fb.c new file mode 100644 index 000000000..c14a19382 --- /dev/null +++ b/drivers/video/fbdev/i740fb.c @@ -0,0 +1,1316 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * i740fb - framebuffer driver for Intel740 + * Copyright (c) 2011 Ondrej Zary + * + * Based on old i740fb driver (c) 2001-2002 Andrey Ulanov + * which was partially based on: + * VGA 16-color framebuffer driver (c) 1999 Ben Pfaff + * and Petr Vandrovec + * i740 driver from XFree86 (c) 1998-1999 Precision Insight, Inc., Cedar Park, + * Texas. + * i740fb by Patrick LERDA, v0.9 + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include