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[crypto] Add memory output constraints for big-integer inline assembly

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The ARM versions of the big-integer inline assembly functions include
constraints to indicate that the output value is modified by the
assembly code.  These constraints are not present in the equivalent
code for the x86 versions.

As of GCC 11, this results in the compiler reporting that the output
values may be uninitialized.

Fix by including the relevant memory output constraints.

Reported-by: Christian Hesse <mail@eworm.de>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2021-06-03 13:34:14 +01:00
parent 74c54461cb
commit f3f568e382
2 changed files with 43 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
src/arch/x86/core/x86_bigint.c
View File

@@ -75,17 +75,18 @@ void bigint_multiply_raw ( const uint32_t *multiplicand0,
* *
* a < 2^{n}, b < 2^{n} => ab < 2^{2n} * a < 2^{n}, b < 2^{n} => ab < 2^{2n}
*/ */
__asm__ __volatile__ ( "mull %4\n\t" __asm__ __volatile__ ( "mull %5\n\t"
"addl %%eax, (%5,%2,4)\n\t" "addl %%eax, (%6,%2,4)\n\t"
"adcl %%edx, 4(%5,%2,4)\n\t" "adcl %%edx, 4(%6,%2,4)\n\t"
"\n1:\n\t" "\n1:\n\t"
"adcl $0, 8(%5,%2,4)\n\t" "adcl $0, 8(%6,%2,4)\n\t"
"inc %2\n\t" "inc %2\n\t"
/* Does not affect CF */ /* Does not affect CF */
"jc 1b\n\t" "jc 1b\n\t"
: "=&a" ( discard_a ), : "=&a" ( discard_a ),
"=&d" ( discard_d ), "=&d" ( discard_d ),
"=&r" ( index ) "=&r" ( index ),
"+m" ( *result )
: "0" ( multiplicand_element ), : "0" ( multiplicand_element ),
"g" ( multiplier_element ), "g" ( multiplier_element ),
"r" ( result_elements ), "r" ( result_elements ),

54
src/arch/x86/include/bits/bigint.h
View File

@@ -25,19 +25,22 @@ typedef uint32_t bigint_element_t;
static inline __attribute__ (( always_inline )) void static inline __attribute__ (( always_inline )) void
bigint_init_raw ( uint32_t *value0, unsigned int size, bigint_init_raw ( uint32_t *value0, unsigned int size,
const void *data, size_t len ) { const void *data, size_t len ) {
long pad_len = ( sizeof ( bigint_t ( size ) ) - len ); bigint_t ( size ) __attribute__ (( may_alias )) *value =
( ( void * ) value0 );
long pad_len = ( sizeof ( *value ) - len );
void *discard_D; void *discard_D;
long discard_c; long discard_c;
/* Copy raw data in reverse order, padding with zeros */ /* Copy raw data in reverse order, padding with zeros */
__asm__ __volatile__ ( "\n1:\n\t" __asm__ __volatile__ ( "\n1:\n\t"
"movb -1(%2,%1), %%al\n\t" "movb -1(%3,%1), %%al\n\t"
"stosb\n\t" "stosb\n\t"
"loop 1b\n\t" "loop 1b\n\t"
"xorl %%eax, %%eax\n\t" "xorl %%eax, %%eax\n\t"
"mov %3, %1\n\t" "mov %4, %1\n\t"
"rep stosb\n\t" "rep stosb\n\t"
: "=&D" ( discard_D ), "=&c" ( discard_c ) : "=&D" ( discard_D ), "=&c" ( discard_c ),
"+m" ( *value )
: "r" ( data ), "g" ( pad_len ), "0" ( value0 ), : "r" ( data ), "g" ( pad_len ), "0" ( value0 ),
"1" ( len ) "1" ( len )
: "eax" ); : "eax" );
@@ -53,6 +56,8 @@ bigint_init_raw ( uint32_t *value0, unsigned int size,
static inline __attribute__ (( always_inline )) void static inline __attribute__ (( always_inline )) void
bigint_add_raw ( const uint32_t *addend0, uint32_t *value0, bigint_add_raw ( const uint32_t *addend0, uint32_t *value0,
unsigned int size ) { unsigned int size ) {
bigint_t ( size ) __attribute__ (( may_alias )) *value =
( ( void * ) value0 );
long index; long index;
void *discard_S; void *discard_S;
long discard_c; long discard_c;
@@ -60,11 +65,11 @@ bigint_add_raw ( const uint32_t *addend0, uint32_t *value0,
__asm__ __volatile__ ( "xor %0, %0\n\t" /* Zero %0 and clear CF */ __asm__ __volatile__ ( "xor %0, %0\n\t" /* Zero %0 and clear CF */
"\n1:\n\t" "\n1:\n\t"
"lodsl\n\t" "lodsl\n\t"
"adcl %%eax, (%3,%0,4)\n\t" "adcl %%eax, (%4,%0,4)\n\t"
"inc %0\n\t" /* Does not affect CF */ "inc %0\n\t" /* Does not affect CF */
"loop 1b\n\t" "loop 1b\n\t"
: "=&r" ( index ), "=&S" ( discard_S ), : "=&r" ( index ), "=&S" ( discard_S ),
"=&c" ( discard_c ) "=&c" ( discard_c ), "+m" ( *value )
: "r" ( value0 ), "1" ( addend0 ), "2" ( size ) : "r" ( value0 ), "1" ( addend0 ), "2" ( size )
: "eax" ); : "eax" );
} }
@@ -79,6 +84,8 @@ bigint_add_raw ( const uint32_t *addend0, uint32_t *value0,
static inline __attribute__ (( always_inline )) void static inline __attribute__ (( always_inline )) void
bigint_subtract_raw ( const uint32_t *subtrahend0, uint32_t *value0, bigint_subtract_raw ( const uint32_t *subtrahend0, uint32_t *value0,
unsigned int size ) { unsigned int size ) {
bigint_t ( size ) __attribute__ (( may_alias )) *value =
( ( void * ) value0 );
long index; long index;
void *discard_S; void *discard_S;
long discard_c; long discard_c;
@@ -86,11 +93,11 @@ bigint_subtract_raw ( const uint32_t *subtrahend0, uint32_t *value0,
__asm__ __volatile__ ( "xor %0, %0\n\t" /* Zero %0 and clear CF */ __asm__ __volatile__ ( "xor %0, %0\n\t" /* Zero %0 and clear CF */
"\n1:\n\t" "\n1:\n\t"
"lodsl\n\t" "lodsl\n\t"
"sbbl %%eax, (%3,%0,4)\n\t" "sbbl %%eax, (%4,%0,4)\n\t"
"inc %0\n\t" /* Does not affect CF */ "inc %0\n\t" /* Does not affect CF */
"loop 1b\n\t" "loop 1b\n\t"
: "=&r" ( index ), "=&S" ( discard_S ), : "=&r" ( index ), "=&S" ( discard_S ),
"=&c" ( discard_c ) "=&c" ( discard_c ), "+m" ( *value )
: "r" ( value0 ), "1" ( subtrahend0 ), : "r" ( value0 ), "1" ( subtrahend0 ),
"2" ( size ) "2" ( size )
: "eax" ); : "eax" );
@@ -104,15 +111,18 @@ bigint_subtract_raw ( const uint32_t *subtrahend0, uint32_t *value0,
*/ */
static inline __attribute__ (( always_inline )) void static inline __attribute__ (( always_inline )) void
bigint_rol_raw ( uint32_t *value0, unsigned int size ) { bigint_rol_raw ( uint32_t *value0, unsigned int size ) {
bigint_t ( size ) __attribute__ (( may_alias )) *value =
( ( void * ) value0 );
long index; long index;
long discard_c; long discard_c;
__asm__ __volatile__ ( "xor %0, %0\n\t" /* Zero %0 and clear CF */ __asm__ __volatile__ ( "xor %0, %0\n\t" /* Zero %0 and clear CF */
"\n1:\n\t" "\n1:\n\t"
"rcll $1, (%2,%0,4)\n\t" "rcll $1, (%3,%0,4)\n\t"
"inc %0\n\t" /* Does not affect CF */ "inc %0\n\t" /* Does not affect CF */
"loop 1b\n\t" "loop 1b\n\t"
: "=&r" ( index ), "=&c" ( discard_c ) : "=&r" ( index ), "=&c" ( discard_c ),
"+m" ( *value )
: "r" ( value0 ), "1" ( size ) ); : "r" ( value0 ), "1" ( size ) );
} }
@@ -124,13 +134,15 @@ bigint_rol_raw ( uint32_t *value0, unsigned int size ) {
*/ */
static inline __attribute__ (( always_inline )) void static inline __attribute__ (( always_inline )) void
bigint_ror_raw ( uint32_t *value0, unsigned int size ) { bigint_ror_raw ( uint32_t *value0, unsigned int size ) {
bigint_t ( size ) __attribute__ (( may_alias )) *value =
( ( void * ) value0 );
long discard_c; long discard_c;
__asm__ __volatile__ ( "clc\n\t" __asm__ __volatile__ ( "clc\n\t"
"\n1:\n\t" "\n1:\n\t"
"rcrl $1, -4(%1,%0,4)\n\t" "rcrl $1, -4(%2,%0,4)\n\t"
"loop 1b\n\t" "loop 1b\n\t"
: "=&c" ( discard_c ) : "=&c" ( discard_c ), "+m" ( *value )
: "r" ( value0 ), "0" ( size ) ); : "r" ( value0 ), "0" ( size ) );
} }
@@ -239,6 +251,8 @@ bigint_max_set_bit_raw ( const uint32_t *value0, unsigned int size ) {
static inline __attribute__ (( always_inline )) void static inline __attribute__ (( always_inline )) void
bigint_grow_raw ( const uint32_t *source0, unsigned int source_size, bigint_grow_raw ( const uint32_t *source0, unsigned int source_size,
uint32_t *dest0, unsigned int dest_size ) { uint32_t *dest0, unsigned int dest_size ) {
bigint_t ( dest_size ) __attribute__ (( may_alias )) *dest =
( ( void * ) dest0 );
long pad_size = ( dest_size - source_size ); long pad_size = ( dest_size - source_size );
void *discard_D; void *discard_D;
void *discard_S; void *discard_S;
@@ -246,10 +260,10 @@ bigint_grow_raw ( const uint32_t *source0, unsigned int source_size,
__asm__ __volatile__ ( "rep movsl\n\t" __asm__ __volatile__ ( "rep movsl\n\t"
"xorl %%eax, %%eax\n\t" "xorl %%eax, %%eax\n\t"
"mov %3, %2\n\t" "mov %4, %2\n\t"
"rep stosl\n\t" "rep stosl\n\t"
: "=&D" ( discard_D ), "=&S" ( discard_S ), : "=&D" ( discard_D ), "=&S" ( discard_S ),
"=&c" ( discard_c ) "=&c" ( discard_c ), "+m" ( *dest )
: "g" ( pad_size ), "0" ( dest0 ), : "g" ( pad_size ), "0" ( dest0 ),
"1" ( source0 ), "2" ( source_size ) "1" ( source0 ), "2" ( source_size )
: "eax" ); : "eax" );
@@ -266,13 +280,15 @@ bigint_grow_raw ( const uint32_t *source0, unsigned int source_size,
static inline __attribute__ (( always_inline )) void static inline __attribute__ (( always_inline )) void
bigint_shrink_raw ( const uint32_t *source0, unsigned int source_size __unused, bigint_shrink_raw ( const uint32_t *source0, unsigned int source_size __unused,
uint32_t *dest0, unsigned int dest_size ) { uint32_t *dest0, unsigned int dest_size ) {
bigint_t ( dest_size ) __attribute__ (( may_alias )) *dest =
( ( void * ) dest0 );
void *discard_D; void *discard_D;
void *discard_S; void *discard_S;
long discard_c; long discard_c;
__asm__ __volatile__ ( "rep movsl\n\t" __asm__ __volatile__ ( "rep movsl\n\t"
: "=&D" ( discard_D ), "=&S" ( discard_S ), : "=&D" ( discard_D ), "=&S" ( discard_S ),
"=&c" ( discard_c ) "=&c" ( discard_c ), "+m" ( *dest )
: "0" ( dest0 ), "1" ( source0 ), : "0" ( dest0 ), "1" ( source0 ),
"2" ( dest_size ) "2" ( dest_size )
: "eax" ); : "eax" );
@@ -289,15 +305,19 @@ bigint_shrink_raw ( const uint32_t *source0, unsigned int source_size __unused,
static inline __attribute__ (( always_inline )) void static inline __attribute__ (( always_inline )) void
bigint_done_raw ( const uint32_t *value0, unsigned int size __unused, bigint_done_raw ( const uint32_t *value0, unsigned int size __unused,
void *out, size_t len ) { void *out, size_t len ) {
struct {
uint8_t bytes[len];
} __attribute__ (( may_alias )) *out_bytes = out;
void *discard_D; void *discard_D;
long discard_c; long discard_c;
/* Copy raw data in reverse order */ /* Copy raw data in reverse order */
__asm__ __volatile__ ( "\n1:\n\t" __asm__ __volatile__ ( "\n1:\n\t"
"movb -1(%2,%1), %%al\n\t" "movb -1(%3,%1), %%al\n\t"
"stosb\n\t" "stosb\n\t"
"loop 1b\n\t" "loop 1b\n\t"
: "=&D" ( discard_D ), "=&c" ( discard_c ) : "=&D" ( discard_D ), "=&c" ( discard_c ),
"+m" ( *out_bytes )
: "r" ( value0 ), "0" ( out ), "1" ( len ) : "r" ( value0 ), "0" ( out ), "1" ( len )
: "eax" ); : "eax" );
} }