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/minix/file.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 fs/minix/file.c (limited to 'fs/minix/file.c') diff --git a/fs/minix/file.c b/fs/minix/file.c new file mode 100644 index 000000000..86e5943cd --- /dev/null +++ b/fs/minix/file.c @@ -0,0 +1,61 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/minix/file.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * minix regular file handling primitives + */ + +#include +#include "minix.h" + +int minix_fsync(struct file *file, loff_t start, loff_t end, int datasync) +{ + return mmb_fsync(file, + &minix_i(file->f_mapping->host)->i_metadata_bhs, + start, end, datasync); +} + +/* + * We have mostly NULLs here: the current defaults are OK for + * the minix filesystem. + */ +const struct file_operations minix_file_operations = { + .llseek = generic_file_llseek, + .read_iter = generic_file_read_iter, + .write_iter = generic_file_write_iter, + .mmap_prepare = generic_file_mmap_prepare, + .fsync = minix_fsync, + .splice_read = filemap_splice_read, +}; + +static int minix_setattr(struct mnt_idmap *idmap, + struct dentry *dentry, struct iattr *attr) +{ + struct inode *inode = d_inode(dentry); + int error; + + error = setattr_prepare(&nop_mnt_idmap, dentry, attr); + if (error) + return error; + + if ((attr->ia_valid & ATTR_SIZE) && + attr->ia_size != i_size_read(inode)) { + error = inode_newsize_ok(inode, attr->ia_size); + if (error) + return error; + + truncate_setsize(inode, attr->ia_size); + minix_truncate(inode); + } + + setattr_copy(&nop_mnt_idmap, inode, attr); + mark_inode_dirty(inode); + return 0; +} + +const struct inode_operations minix_file_inode_operations = { + .setattr = minix_setattr, + .getattr = minix_getattr, +}; -- cgit v1.3.1