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Fix undefined behaviour in left shifts

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Due to the integer promotion rules of the C language, the unsigned char
values are promoted to a signed integer (and not an unsigned integer)
before being shifted. But the result of a left shift on a signed type is
undefined if the resulting value can't be represented in the signed
type.

GCC's Undefined Behavior Sanitizer (ubsan), enabled with the option
-fsanitize=undefined, detects this type of problem at runtime with the
following warning: "left shift of X by Y places cannot be represented in
type 'int'".

Fixed with an explicit cast to unsigned integer.
This commit is contained in:
Jef Driesen 2018-11-30 19:23:53 +01:00
parent 43303eadf6
commit ed21d776dd
1 changed files with 24 additions and 9 deletions
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33
src/array.c
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@ -167,7 +167,7 @@ array_uint_be (const unsigned char data[], unsigned int n)
unsigned int value = 0;
for (unsigned int i = 0; i < n; ++i) {
shift -= 8;
value |= data[i] << shift;
value |= (unsigned int) data[i] << shift;
}
return value;
}
@ -178,7 +178,7 @@ array_uint_le (const unsigned char data[], unsigned int n)
unsigned int shift = 0;
unsigned int value = 0;
for (unsigned int i = 0; i < n; ++i) {
value |= data[i] << shift;
value |= (unsigned int) data[i] << shift;
shift += 8;
}
return value;
@ -187,21 +187,30 @@ array_uint_le (const unsigned char data[], unsigned int n)
unsigned int
array_uint32_be (const unsigned char data[])
{
return (data[0] << 24) + (data[1] << 16) + (data[2] << 8) + data[3];
return ((unsigned int) data[0] << 24) |
((unsigned int) data[1] << 16) |
((unsigned int) data[2] << 8) |
((unsigned int) data[3] << 0);
}
unsigned int
array_uint32_le (const unsigned char data[])
{
return data[0] + (data[1] << 8) + (data[2] << 16) + (data[3] << 24);
return ((unsigned int) data[0] << 0) |
((unsigned int) data[1] << 8) |
((unsigned int) data[2] << 16) |
((unsigned int) data[3] << 24);
}
unsigned int
array_uint32_word_be (const unsigned char data[])
{
return data[1] + (data[0] << 8) + (data[3] << 16) + (data[2] << 24);
return ((unsigned int) data[0] << 8) |
((unsigned int) data[1] << 0) |
((unsigned int) data[2] << 24) |
((unsigned int) data[3] << 16);
}
@ -218,7 +227,9 @@ array_uint32_le_set (unsigned char data[], const unsigned int input)
unsigned int
array_uint24_be (const unsigned char data[])
{
return (data[0] << 16) + (data[1] << 8) + data[2];
return ((unsigned int) data[0] << 16) |
((unsigned int) data[1] << 8) |
((unsigned int) data[2] << 0);
}
@ -234,20 +245,24 @@ array_uint24_be_set (unsigned char data[], const unsigned int input)
unsigned int
array_uint24_le (const unsigned char data[])
{
return data[0] + (data[1] << 8) + (data[2] << 16);
return ((unsigned int) data[0] << 0) |
((unsigned int) data[1] << 8) |
((unsigned int) data[2] << 16);
}
unsigned short
array_uint16_be (const unsigned char data[])
{
return (data[0] << 8) + data[1];
return ((unsigned int) data[0] << 8) |
((unsigned int) data[1] << 0);
}
unsigned short
array_uint16_le (const unsigned char data[])
{
return data[0] + (data[1] << 8);
return ((unsigned int) data[0] << 0) |
((unsigned int) data[1] << 8);
}
unsigned char