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/dir.c | 105 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 105 insertions(+) create mode 100644 fs/efs/dir.c (limited to 'fs/efs/dir.c') diff --git a/fs/efs/dir.c b/fs/efs/dir.c new file mode 100644 index 000000000..35ad0092c --- /dev/null +++ b/fs/efs/dir.c @@ -0,0 +1,105 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * dir.c + * + * Copyright (c) 1999 Al Smith + */ + +#include +#include +#include "efs.h" + +static int efs_readdir(struct file *, struct dir_context *); + +const struct file_operations efs_dir_operations = { + .llseek = generic_file_llseek, + .read = generic_read_dir, + .iterate_shared = efs_readdir, + .setlease = generic_setlease, +}; + +const struct inode_operations efs_dir_inode_operations = { + .lookup = efs_lookup, +}; + +static int efs_readdir(struct file *file, struct dir_context *ctx) +{ + struct inode *inode = file_inode(file); + efs_block_t block; + int slot; + + if (inode->i_size & (EFS_DIRBSIZE-1)) + pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE\n", + __func__); + + /* work out where this entry can be found */ + block = ctx->pos >> EFS_DIRBSIZE_BITS; + + /* each block contains at most 256 slots */ + slot = ctx->pos & 0xff; + + /* look at all blocks */ + while (block < inode->i_blocks) { + struct efs_dir *dirblock; + struct buffer_head *bh; + + /* read the dir block */ + bh = sb_bread(inode->i_sb, efs_bmap(inode, block)); + + if (!bh) { + pr_err("%s(): failed to read dir block %d\n", + __func__, block); + break; + } + + dirblock = (struct efs_dir *) bh->b_data; + + if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) { + pr_err("%s(): invalid directory block\n", __func__); + brelse(bh); + break; + } + + for (; slot < dirblock->slots; slot++) { + struct efs_dentry *dirslot; + efs_ino_t inodenum; + const char *nameptr; + int namelen; + + if (dirblock->space[slot] == 0) + continue; + + dirslot = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot)); + + inodenum = be32_to_cpu(dirslot->inode); + namelen = dirslot->namelen; + nameptr = dirslot->name; + pr_debug("%s(): block %d slot %d/%d: inode %u, name \"%s\", namelen %u\n", + __func__, block, slot, dirblock->slots-1, + inodenum, nameptr, namelen); + if (!namelen) + continue; + /* found the next entry */ + ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot; + + /* sanity check */ + if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) { + pr_warn("directory entry %d exceeds directory block\n", + slot); + continue; + } + + /* copy filename and data in dirslot */ + if (!dir_emit(ctx, nameptr, namelen, inodenum, DT_UNKNOWN)) { + brelse(bh); + return 0; + } + } + brelse(bh); + + slot = 0; + block++; + } + ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot; + return 0; +} -- cgit v1.3.1