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/sbuslib.h | 63 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 drivers/video/fbdev/sbuslib.h (limited to 'drivers/video/fbdev/sbuslib.h') diff --git a/drivers/video/fbdev/sbuslib.h b/drivers/video/fbdev/sbuslib.h new file mode 100644 index 000000000..e9af2dc93 --- /dev/null +++ b/drivers/video/fbdev/sbuslib.h @@ -0,0 +1,63 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* sbuslib.h: SBUS fb helper library interfaces */ +#ifndef _SBUSLIB_H +#define _SBUSLIB_H + +struct device_node; +struct fb_info; +struct fb_var_screeninfo; +struct vm_area_struct; + +struct sbus_mmap_map { + unsigned long voff; + unsigned long poff; + unsigned long size; +}; + +#define SBUS_MMAP_FBSIZE(n) (-n) +#define SBUS_MMAP_EMPTY 0x80000000 + +extern void sbusfb_fill_var(struct fb_var_screeninfo *var, + struct device_node *dp, int bpp); +extern int sbusfb_mmap_helper(const struct sbus_mmap_map *map, + unsigned long physbase, unsigned long fbsize, + unsigned long iospace, + struct vm_area_struct *vma); +int sbusfb_ioctl_helper(unsigned long cmd, unsigned long arg, + struct fb_info *info, + int type, int fb_depth, unsigned long fb_size); +int sbusfb_compat_ioctl(struct fb_info *info, unsigned int cmd, + unsigned long arg); + +/* + * Initialize struct fb_ops for SBUS I/O. + */ + +#define __FB_DEFAULT_SBUS_OPS_RDWR(__prefix) \ + .fb_read = fb_io_read, \ + .fb_write = fb_io_write + +#define __FB_DEFAULT_SBUS_OPS_DRAW(__prefix) \ + .fb_fillrect = cfb_fillrect, \ + .fb_copyarea = cfb_copyarea, \ + .fb_imageblit = cfb_imageblit + +#ifdef CONFIG_COMPAT +#define __FB_DEFAULT_SBUS_OPS_IOCTL(__prefix) \ + .fb_ioctl = __prefix ## _sbusfb_ioctl, \ + .fb_compat_ioctl = sbusfb_compat_ioctl +#else +#define __FB_DEFAULT_SBUS_OPS_IOCTL(__prefix) \ + .fb_ioctl = __prefix ## _sbusfb_ioctl +#endif + +#define __FB_DEFAULT_SBUS_OPS_MMAP(__prefix) \ + .fb_mmap = __prefix ## _sbusfb_mmap + +#define FB_DEFAULT_SBUS_OPS(__prefix) \ + __FB_DEFAULT_SBUS_OPS_RDWR(__prefix), \ + __FB_DEFAULT_SBUS_OPS_DRAW(__prefix), \ + __FB_DEFAULT_SBUS_OPS_IOCTL(__prefix), \ + __FB_DEFAULT_SBUS_OPS_MMAP(__prefix) + +#endif /* _SBUSLIB_H */ -- cgit v1.3.1