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/arm/mm/physaddr.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 arch/arm/mm/physaddr.c (limited to 'arch/arm/mm/physaddr.c') diff --git a/arch/arm/mm/physaddr.c b/arch/arm/mm/physaddr.c new file mode 100644 index 000000000..1a37ebfac --- /dev/null +++ b/arch/arm/mm/physaddr.c @@ -0,0 +1,58 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include + +#include +#include +#include +#include + +#include "mm.h" + +static inline bool __virt_addr_valid(unsigned long x) +{ + /* + * high_memory does not get immediately defined, and there + * are early callers of __pa() against PAGE_OFFSET + */ + if (!high_memory && x >= PAGE_OFFSET) + return true; + + if (high_memory && x >= PAGE_OFFSET && x < (unsigned long)high_memory) + return true; + + /* + * MAX_DMA_ADDRESS is a virtual address that may not correspond to an + * actual physical address. Enough code relies on __pa(MAX_DMA_ADDRESS) + * that we just need to work around it and always return true. + */ + if (x == MAX_DMA_ADDRESS) + return true; + + return false; +} + +phys_addr_t __virt_to_phys(unsigned long x) +{ + WARN(!__virt_addr_valid(x), + "virt_to_phys used for non-linear address: %px (%pS)\n", + (void *)x, (void *)x); + + return __virt_to_phys_nodebug(x); +} +EXPORT_SYMBOL(__virt_to_phys); + +phys_addr_t __phys_addr_symbol(unsigned long x) +{ + /* This is bounds checking against the kernel image only. + * __pa_symbol should only be used on kernel symbol addresses. + */ + VIRTUAL_BUG_ON(x < (unsigned long)KERNEL_START || + x > (unsigned long)KERNEL_END); + + return __pa_symbol_nodebug(x); +} +EXPORT_SYMBOL(__phys_addr_symbol); -- cgit v1.3.1