diff options
Diffstat (limited to 'arch/x86/mm/maccess.c')
| -rw-r--r-- | arch/x86/mm/maccess.c | 29 |
1 files changed, 24 insertions, 5 deletions
diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c index 5a53c2cc169c..42115ac079cf 100644 --- a/arch/x86/mm/maccess.c +++ b/arch/x86/mm/maccess.c @@ -3,18 +3,37 @@ #include <linux/uaccess.h> #include <linux/kernel.h> +#include <asm/vsyscall.h> + #ifdef CONFIG_X86_64 bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) { unsigned long vaddr = (unsigned long)unsafe_src; /* - * Range covering the highest possible canonical userspace address - * as well as non-canonical address range. For the canonical range - * we also need to include the userspace guard page. + * Do not allow userspace addresses. This disallows + * normal userspace and the userspace guard page: + */ + if (vaddr < TASK_SIZE_MAX + PAGE_SIZE) + return false; + + /* + * Reading from the vsyscall page may cause an unhandled fault in + * certain cases. Though it is at an address above TASK_SIZE_MAX, it is + * usually considered as a user space address. */ - return vaddr >= TASK_SIZE_MAX + PAGE_SIZE && - __is_canonical_address(vaddr, boot_cpu_data.x86_virt_bits); + if (is_vsyscall_vaddr(vaddr)) + return false; + + /* + * Allow everything during early boot before 'x86_virt_bits' + * is initialized. Needed for instruction decoding in early + * exception handlers. + */ + if (!boot_cpu_data.x86_virt_bits) + return true; + + return __is_canonical_address(vaddr, boot_cpu_data.x86_virt_bits); } #else bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) |