bitcoin#18843: warn on potentially uninitialized reads

This commit is contained in:
Kittywhiskers Van Gogh 2020-05-01 14:05:48 +02:00
parent 49921dbdd8
commit 638fdf25fd
3 changed files with 8 additions and 3 deletions

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@ -367,6 +367,7 @@ if test "x$enable_werror" = "xyes"; then
AX_CHECK_COMPILE_FLAG([-Werror=unused-variable],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=unused-variable"],,[[$CXXFLAG_WERROR]]) AX_CHECK_COMPILE_FLAG([-Werror=unused-variable],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=unused-variable"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Werror=date-time],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=date-time"],,[[$CXXFLAG_WERROR]]) AX_CHECK_COMPILE_FLAG([-Werror=date-time],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=date-time"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Werror=return-type],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=return-type"],,[[$CXXFLAG_WERROR]]) AX_CHECK_COMPILE_FLAG([-Werror=return-type],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=return-type"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Werror=conditional-uninitialized],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=conditional-uninitialized"],,[[$CXXFLAG_WERROR]])
fi fi
if test "x$CXXFLAGS_overridden" = "xno"; then if test "x$CXXFLAGS_overridden" = "xno"; then
@ -381,6 +382,7 @@ if test "x$CXXFLAGS_overridden" = "xno"; then
AX_CHECK_COMPILE_FLAG([-Wredundant-decls],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wredundant-decls"],,[[$CXXFLAG_WERROR]]) AX_CHECK_COMPILE_FLAG([-Wredundant-decls],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wredundant-decls"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Wunused-variable],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wunused-variable"],,[[$CXXFLAG_WERROR]]) AX_CHECK_COMPILE_FLAG([-Wunused-variable],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wunused-variable"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Wdate-time],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wdate-time"],,[[$CXXFLAG_WERROR]]) AX_CHECK_COMPILE_FLAG([-Wdate-time],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wdate-time"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Wconditional-uninitialized],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wconditional-uninitialized"],,[[$CXXFLAG_WERROR]])
## Some compilers (gcc) ignore unknown -Wno-* options, but warn about all ## Some compilers (gcc) ignore unknown -Wno-* options, but warn about all
## unknown options if any other warning is produced. Test the -Wfoo case, and ## unknown options if any other warning is produced. Test the -Wfoo case, and

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@ -30,7 +30,7 @@ LEVELDB_CPPFLAGS_INT += -DLEVELDB_PLATFORM_POSIX
endif endif
leveldb_libleveldb_a_CPPFLAGS = $(AM_CPPFLAGS) $(LEVELDB_CPPFLAGS_INT) $(LEVELDB_CPPFLAGS) leveldb_libleveldb_a_CPPFLAGS = $(AM_CPPFLAGS) $(LEVELDB_CPPFLAGS_INT) $(LEVELDB_CPPFLAGS)
leveldb_libleveldb_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS) leveldb_libleveldb_a_CXXFLAGS = $(filter-out -Wconditional-uninitialized -Werror=conditional-uninitialized, $(AM_CXXFLAGS)) $(PIE_FLAGS)
leveldb_libleveldb_a_SOURCES= leveldb_libleveldb_a_SOURCES=
leveldb_libleveldb_a_SOURCES += leveldb/port/atomic_pointer.h leveldb_libleveldb_a_SOURCES += leveldb/port/atomic_pointer.h

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@ -100,7 +100,10 @@ static bool GetHWRand(unsigned char* ent32) {
// Not all assemblers support the rdrand instruction, write it in hex. // Not all assemblers support the rdrand instruction, write it in hex.
#ifdef __i386__ #ifdef __i386__
for (int iter = 0; iter < 4; ++iter) { for (int iter = 0; iter < 4; ++iter) {
uint32_t r1, r2; // Initialize to 0 to silence a compiler warning that r1 or r2 may be used
// uninitialized. Even if rdrand fails (!ok) it will set the output to 0,
// but there is no way that the compiler could know that.
uint32_t r1 = 0, r2 = 0;
__asm__ volatile (".byte 0x0f, 0xc7, 0xf0;" // rdrand %eax __asm__ volatile (".byte 0x0f, 0xc7, 0xf0;" // rdrand %eax
".byte 0x0f, 0xc7, 0xf2;" // rdrand %edx ".byte 0x0f, 0xc7, 0xf2;" // rdrand %edx
"setc %2" : "setc %2" :
@ -110,7 +113,7 @@ static bool GetHWRand(unsigned char* ent32) {
WriteLE32(ent32 + 8 * iter + 4, r2); WriteLE32(ent32 + 8 * iter + 4, r2);
} }
#else #else
uint64_t r1, r2, r3, r4; uint64_t r1 = 0, r2 = 0, r3 = 0, r4 = 0; // See above why we initialize to 0.
__asm__ volatile (".byte 0x48, 0x0f, 0xc7, 0xf0, " // rdrand %rax __asm__ volatile (".byte 0x48, 0x0f, 0xc7, 0xf0, " // rdrand %rax
"0x48, 0x0f, 0xc7, 0xf3, " // rdrand %rbx "0x48, 0x0f, 0xc7, 0xf3, " // rdrand %rbx
"0x48, 0x0f, 0xc7, 0xf1, " // rdrand %rcx "0x48, 0x0f, 0xc7, 0xf1, " // rdrand %rcx