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1// SPDX-License-Identifier: GPL-2.02#include <linux/compiler.h>3#include <linux/errno.h>4#include <linux/export.h>5#include <linux/fault-inject-usercopy.h>6#include <linux/instrumented.h>7#include <linux/kernel.h>8#include <linux/nospec.h>9#include <linux/string.h>10#include <linux/uaccess.h>11#include <linux/wordpart.h>12 13/* out-of-line parts */14 15#if !defined(INLINE_COPY_FROM_USER) || defined(CONFIG_RUST)16unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)17{18 return _inline_copy_from_user(to, from, n);19}20EXPORT_SYMBOL(_copy_from_user);21#endif22 23#if !defined(INLINE_COPY_TO_USER) || defined(CONFIG_RUST)24unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)25{26 return _inline_copy_to_user(to, from, n);27}28EXPORT_SYMBOL(_copy_to_user);29#endif30 31/**32 * check_zeroed_user: check if a userspace buffer only contains zero bytes33 * @from: Source address, in userspace.34 * @size: Size of buffer.35 *36 * This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for37 * userspace addresses (and is more efficient because we don't care where the38 * first non-zero byte is).39 *40 * Returns:41 * * 0: There were non-zero bytes present in the buffer.42 * * 1: The buffer was full of zero bytes.43 * * -EFAULT: access to userspace failed.44 */45int check_zeroed_user(const void __user *from, size_t size)46{47 unsigned long val;48 uintptr_t align = (uintptr_t) from % sizeof(unsigned long);49 50 if (unlikely(size == 0))51 return 1;52 53 from -= align;54 size += align;55 56 if (!user_read_access_begin(from, size))57 return -EFAULT;58 59 unsafe_get_user(val, (unsigned long __user *) from, err_fault);60 if (align)61 val &= ~aligned_byte_mask(align);62 63 while (size > sizeof(unsigned long)) {64 if (unlikely(val))65 goto done;66 67 from += sizeof(unsigned long);68 size -= sizeof(unsigned long);69 70 unsafe_get_user(val, (unsigned long __user *) from, err_fault);71 }72 73 if (size < sizeof(unsigned long))74 val &= aligned_byte_mask(size);75 76done:77 user_read_access_end();78 return (val == 0);79err_fault:80 user_read_access_end();81 return -EFAULT;82}83EXPORT_SYMBOL(check_zeroed_user);84