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/efs/file.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 fs/efs/file.c (limited to 'fs/efs/file.c') diff --git a/fs/efs/file.c b/fs/efs/file.c new file mode 100644 index 000000000..9153dfe79 --- /dev/null +++ b/fs/efs/file.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * file.c + * + * Copyright (c) 1999 Al Smith + * + * Portions derived from work (c) 1995,1996 Christian Vogelgsang. + */ + +#include +#include "efs.h" + +int efs_get_block(struct inode *inode, sector_t iblock, + struct buffer_head *bh_result, int create) +{ + int error = -EROFS; + long phys; + + if (create) + return error; + if (iblock >= inode->i_blocks) + return 0; + + phys = efs_map_block(inode, iblock); + if (phys) + map_bh(bh_result, inode->i_sb, phys); + return 0; +} + +int efs_bmap(struct inode *inode, efs_block_t block) { + + if (block < 0) { + pr_warn("%s(): block < 0\n", __func__); + return 0; + } + + /* are we about to read past the end of a file ? */ + if (!(block < inode->i_blocks)) + return 0; + + return efs_map_block(inode, block); +} -- cgit v1.3.1