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/microblaze/lib/libgcc.h | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) create mode 100644 arch/microblaze/lib/libgcc.h (limited to 'arch/microblaze/lib/libgcc.h') diff --git a/arch/microblaze/lib/libgcc.h b/arch/microblaze/lib/libgcc.h new file mode 100644 index 000000000..a909366c2 --- /dev/null +++ b/arch/microblaze/lib/libgcc.h @@ -0,0 +1,33 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_LIBGCC_H +#define __ASM_LIBGCC_H + +#include + +typedef int word_type __attribute__ ((mode (__word__))); + +#ifdef __BIG_ENDIAN +struct DWstruct { + int high, low; +}; +#elif defined(__LITTLE_ENDIAN) +struct DWstruct { + int low, high; +}; +#else +#error I feel sick. +#endif + +typedef union { + struct DWstruct s; + long long ll; +} DWunion; + +extern long long __ashldi3(long long u, word_type b); +extern long long __ashrdi3(long long u, word_type b); +extern word_type __cmpdi2(long long a, long long b); +extern long long __lshrdi3(long long u, word_type b); +extern long long __muldi3(long long u, long long v); +extern word_type __ucmpdi2(unsigned long long a, unsigned long long b); + +#endif /* __ASM_LIBGCC_H */ -- cgit v1.3.1