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/adfs/dir_f.h | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 fs/adfs/dir_f.h (limited to 'fs/adfs/dir_f.h') diff --git a/fs/adfs/dir_f.h b/fs/adfs/dir_f.h new file mode 100644 index 000000000..4e6c53d59 --- /dev/null +++ b/fs/adfs/dir_f.h @@ -0,0 +1,61 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * linux/fs/adfs/dir_f.h + * + * Copyright (C) 1999 Russell King + * + * Structures of directories on the F format disk + */ +#ifndef ADFS_DIR_F_H +#define ADFS_DIR_F_H + +/* + * Directory header + */ +struct adfs_dirheader { + __u8 startmasseq; + __u8 startname[4]; +} __attribute__((packed)); + +#define ADFS_NEWDIR_SIZE 2048 +#define ADFS_NUM_DIR_ENTRIES 77 + +/* + * Directory entries + */ +struct adfs_direntry { +#define ADFS_F_NAME_LEN 10 + char dirobname[ADFS_F_NAME_LEN]; + __u8 dirload[4]; + __u8 direxec[4]; + __u8 dirlen[4]; + __u8 dirinddiscadd[3]; + __u8 newdiratts; +} __attribute__((packed)); + +/* + * Directory tail + */ +struct adfs_olddirtail { + __u8 dirlastmask; + char dirname[10]; + __u8 dirparent[3]; + char dirtitle[19]; + __u8 reserved[14]; + __u8 endmasseq; + __u8 endname[4]; + __u8 dircheckbyte; +} __attribute__((packed)); + +struct adfs_newdirtail { + __u8 dirlastmask; + __u8 reserved[2]; + __u8 dirparent[3]; + char dirtitle[19]; + char dirname[10]; + __u8 endmasseq; + __u8 endname[4]; + __u8 dircheckbyte; +} __attribute__((packed)); + +#endif -- cgit v1.3.1