change system file

hc

2024-10-09 244b2c5ca8b14627e4a17755e5922221e121c771

 kernel/lib/usercopy.c
..
..
@@ -1,5 +1,9 @@
1
1
 // SPDX-License-Identifier: GPL-2.0
2
+#include <linux/bitops.h>
3
+#include <linux/fault-inject-usercopy.h>
4
+#include <linux/instrumented.h>
2
5
 #include <linux/uaccess.h>
6
+#include <linux/nospec.h>
3
7
 
4
8
 /* out-of-line parts */
5
9
 
..
..
@@ -8,8 +12,14 @@
8
12
 {
9
13
 	unsigned long res = n;
10
14
 	might_fault();
11
-	if (likely(access_ok(VERIFY_READ, from, n))) {
12
-		kasan_check_write(to, n);
15
+	if (!should_fail_usercopy() && likely(access_ok(from, n))) {
16
+		/*
17
+		 * Ensure that bad access_ok() speculation will not
18
+		 * lead to nasty side effects *after* the copy is
19
+		 * finished:
20
+		 */
21
+		barrier_nospec();
22
+		instrument_copy_from_user(to, from, n);
13
23
 		res = raw_copy_from_user(to, from, n);
14
24
 	}
15
25
 	if (unlikely(res))
..
..
@@ -23,11 +33,67 @@
23
33
 unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
24
34
 {
25
35
 	might_fault();
26
-	if (likely(access_ok(VERIFY_WRITE, to, n))) {
27
-		kasan_check_read(from, n);
36
+	if (should_fail_usercopy())
37
+		return n;
38
+	if (likely(access_ok(to, n))) {
39
+		instrument_copy_to_user(to, from, n);
28
40
 		n = raw_copy_to_user(to, from, n);
29
41
 	}
30
42
 	return n;
31
43
 }
32
44
 EXPORT_SYMBOL(_copy_to_user);
33
45
 #endif
46
+
47
+/**
48
+ * check_zeroed_user: check if a userspace buffer only contains zero bytes
49
+ * @from: Source address, in userspace.
50
+ * @size: Size of buffer.
51
+ *
52
+ * This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for
53
+ * userspace addresses (and is more efficient because we don't care where the
54
+ * first non-zero byte is).
55
+ *
56
+ * Returns:
57
+ *  * 0: There were non-zero bytes present in the buffer.
58
+ *  * 1: The buffer was full of zero bytes.
59
+ *  * -EFAULT: access to userspace failed.
60
+ */
61
+int check_zeroed_user(const void __user *from, size_t size)
62
+{
63
+	unsigned long val;
64
+	uintptr_t align = (uintptr_t) from % sizeof(unsigned long);
65
+
66
+	if (unlikely(size == 0))
67
+		return 1;
68
+
69
+	from -= align;
70
+	size += align;
71
+
72
+	if (!user_read_access_begin(from, size))
73
+		return -EFAULT;
74
+
75
+	unsafe_get_user(val, (unsigned long __user *) from, err_fault);
76
+	if (align)
77
+		val &= ~aligned_byte_mask(align);
78
+
79
+	while (size > sizeof(unsigned long)) {
80
+		if (unlikely(val))
81
+			goto done;
82
+
83
+		from += sizeof(unsigned long);
84
+		size -= sizeof(unsigned long);
85
+
86
+		unsafe_get_user(val, (unsigned long __user *) from, err_fault);
87
+	}
88
+
89
+	if (size < sizeof(unsigned long))
90
+		val &= aligned_byte_mask(size);
91
+
92
+done:
93
+	user_read_access_end();
94
+	return (val == 0);
95
+err_fault:
96
+	user_read_access_end();
97
+	return -EFAULT;
98
+}
99
+EXPORT_SYMBOL(check_zeroed_user);