diff options
Diffstat (limited to 'arch/x86/mm/maccess.c')
| -rw-r--r-- | arch/x86/mm/maccess.c | 38 |
1 files changed, 26 insertions, 12 deletions
diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c index e1d7d7477c22..42115ac079cf 100644 --- a/arch/x86/mm/maccess.c +++ b/arch/x86/mm/maccess.c @@ -3,26 +3,40 @@ #include <linux/uaccess.h> #include <linux/kernel.h> -#ifdef CONFIG_X86_64 -static __always_inline u64 canonical_address(u64 vaddr, u8 vaddr_bits) -{ - return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits); -} +#include <asm/vsyscall.h> -bool probe_kernel_read_allowed(const void *unsafe_src, size_t size) +#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: */ - return vaddr >= TASK_SIZE_MAX + PAGE_SIZE && - canonical_address(vaddr, boot_cpu_data.x86_virt_bits) == vaddr; + 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. + */ + 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 probe_kernel_read_allowed(const void *unsafe_src, size_t size) +bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) { return (unsigned long)unsafe_src >= TASK_SIZE_MAX; } |