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/btrfs/ref-verify.h | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 fs/btrfs/ref-verify.h (limited to 'fs/btrfs/ref-verify.h') diff --git a/fs/btrfs/ref-verify.h b/fs/btrfs/ref-verify.h new file mode 100644 index 000000000..1ce544d53 --- /dev/null +++ b/fs/btrfs/ref-verify.h @@ -0,0 +1,58 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2014 Facebook. All rights reserved. + */ + +#ifndef BTRFS_REF_VERIFY_H +#define BTRFS_REF_VERIFY_H + +#include +#include + +struct btrfs_fs_info; +struct btrfs_ref; + +#ifdef CONFIG_BTRFS_DEBUG + +#include + +int btrfs_build_ref_tree(struct btrfs_fs_info *fs_info); +void btrfs_free_ref_cache(struct btrfs_fs_info *fs_info); +int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info, + const struct btrfs_ref *generic_ref); +void btrfs_free_ref_tree_range(struct btrfs_fs_info *fs_info, u64 start, + u64 len); + +static inline void btrfs_init_ref_verify(struct btrfs_fs_info *fs_info) +{ + spin_lock_init(&fs_info->ref_verify_lock); + fs_info->block_tree = RB_ROOT; +} +#else +static inline int btrfs_build_ref_tree(struct btrfs_fs_info *fs_info) +{ + return 0; +} + +static inline void btrfs_free_ref_cache(struct btrfs_fs_info *fs_info) +{ +} + +static inline int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info, + const struct btrfs_ref *generic_ref) +{ + return 0; +} + +static inline void btrfs_free_ref_tree_range(struct btrfs_fs_info *fs_info, + u64 start, u64 len) +{ +} + +static inline void btrfs_init_ref_verify(struct btrfs_fs_info *fs_info) +{ +} + +#endif /* CONFIG_BTRFS_DEBUG */ + +#endif -- cgit v1.3.1