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 --- arch/x86/lib/putuser.S | 156 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 156 insertions(+) create mode 100644 arch/x86/lib/putuser.S (limited to 'arch/x86/lib/putuser.S') diff --git a/arch/x86/lib/putuser.S b/arch/x86/lib/putuser.S new file mode 100644 index 000000000..46d9e9b98 --- /dev/null +++ b/arch/x86/lib/putuser.S @@ -0,0 +1,156 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * __put_user functions. + * + * (C) Copyright 2005 Linus Torvalds + * (C) Copyright 2005 Andi Kleen + * (C) Copyright 2008 Glauber Costa + * + * These functions have a non-standard call interface + * to make them more efficient, especially as they + * return an error value in addition to the "real" + * return value. + */ +#include +#include +#include +#include +#include +#include +#include + +/* + * __put_user_X + * + * Inputs: %eax[:%edx] contains the data + * %ecx contains the address + * + * Outputs: %ecx is error code (0 or -EFAULT) + * + * Clobbers: %ebx needed for task pointer + * + * These functions should not modify any other registers, + * as they get called from within inline assembly. + */ + +.macro check_range size:req +.if IS_ENABLED(CONFIG_X86_64) + mov %rcx, %rbx + sar $63, %rbx + or %rbx, %rcx +.else + cmp $TASK_SIZE_MAX-\size+1, %ecx + jae .Lbad_put_user +.endif +.endm + +.text +SYM_FUNC_START(__put_user_1) + ANNOTATE_NOENDBR + check_range size=1 + ASM_STAC +1: movb %al,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_1) +EXPORT_SYMBOL(__put_user_1) + +SYM_FUNC_START(__put_user_nocheck_1) + ANNOTATE_NOENDBR + ASM_STAC +2: movb %al,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_nocheck_1) +EXPORT_SYMBOL(__put_user_nocheck_1) + +SYM_FUNC_START(__put_user_2) + ANNOTATE_NOENDBR + check_range size=2 + ASM_STAC +3: movw %ax,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_2) +EXPORT_SYMBOL(__put_user_2) + +SYM_FUNC_START(__put_user_nocheck_2) + ANNOTATE_NOENDBR + ASM_STAC +4: movw %ax,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_nocheck_2) +EXPORT_SYMBOL(__put_user_nocheck_2) + +SYM_FUNC_START(__put_user_4) + ANNOTATE_NOENDBR + check_range size=4 + ASM_STAC +5: movl %eax,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_4) +EXPORT_SYMBOL(__put_user_4) + +SYM_FUNC_START(__put_user_nocheck_4) + ANNOTATE_NOENDBR + ASM_STAC +6: movl %eax,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_nocheck_4) +EXPORT_SYMBOL(__put_user_nocheck_4) + +SYM_FUNC_START(__put_user_8) + ANNOTATE_NOENDBR + check_range size=8 + ASM_STAC +7: mov %_ASM_AX,(%_ASM_CX) +#ifdef CONFIG_X86_32 +8: movl %edx,4(%_ASM_CX) +#endif + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_8) +EXPORT_SYMBOL(__put_user_8) + +SYM_FUNC_START(__put_user_nocheck_8) + ANNOTATE_NOENDBR + ASM_STAC +9: mov %_ASM_AX,(%_ASM_CX) +#ifdef CONFIG_X86_32 +10: movl %edx,4(%_ASM_CX) +#endif + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_nocheck_8) +EXPORT_SYMBOL(__put_user_nocheck_8) + +SYM_CODE_START_LOCAL(__put_user_handle_exception) + ASM_CLAC +.Lbad_put_user: + movl $-EFAULT,%ecx + RET +SYM_CODE_END(__put_user_handle_exception) + + _ASM_EXTABLE_UA(1b, __put_user_handle_exception) + _ASM_EXTABLE_UA(2b, __put_user_handle_exception) + _ASM_EXTABLE_UA(3b, __put_user_handle_exception) + _ASM_EXTABLE_UA(4b, __put_user_handle_exception) + _ASM_EXTABLE_UA(5b, __put_user_handle_exception) + _ASM_EXTABLE_UA(6b, __put_user_handle_exception) + _ASM_EXTABLE_UA(7b, __put_user_handle_exception) + _ASM_EXTABLE_UA(9b, __put_user_handle_exception) +#ifdef CONFIG_X86_32 + _ASM_EXTABLE_UA(8b, __put_user_handle_exception) + _ASM_EXTABLE_UA(10b, __put_user_handle_exception) +#endif -- cgit v1.3.1