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8170981: Possible access to char array with negative index

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Check arithmetic before trying to access array by index.

Reviewed-by: rprotacio, dholmes, gziemski
This commit is contained in:
Lutz Schmidt 2016-12-22 15:01:20 -06:00
parent f82263efb8
commit 9b98f88304
1 changed files with 13 additions and 6 deletions
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19
hotspot/src/share/vm/runtime/globals.cpp
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@ -469,14 +469,18 @@ void Flag::print_on(outputStream* st, bool withComments, bool printRanges) {
} }
if (!printRanges) { if (!printRanges) {
// Use some named constants to make code more readable.
const unsigned int nSpaces = 10;
const unsigned int maxFlagLen = 40 + nSpaces;
// The print below assumes that the flag name is 40 characters or less. // The print below assumes that the flag name is 40 characters or less.
// This works for most flags, but there are exceptions. Our longest flag // This works for most flags, but there are exceptions. Our longest flag
// name right now is UseAdaptiveGenerationSizePolicyAtMajorCollection and // name right now is UseAdaptiveGenerationSizePolicyAtMajorCollection and
// its minor collection buddy. These are 48 characters. We use a buffer of // its minor collection buddy. These are 48 characters. We use a buffer of
// 10 spaces below to adjust the space between the flag value and the // nSpaces spaces below to adjust the space between the flag value and the
// column of flag type and origin that is printed in the end of the line. // column of flag type and origin that is printed in the end of the line.
char spaces[10 + 1] = " "; char spaces[nSpaces + 1] = " ";
st->print("%9s %-40s = ", _type, _name); st->print("%9s %-*s = ", _type, maxFlagLen-nSpaces, _name);
if (is_bool()) { if (is_bool()) {
st->print("%-20s", get_bool() ? "true" : "false"); st->print("%-20s", get_bool() ? "true" : "false");
@ -509,9 +513,12 @@ void Flag::print_on(outputStream* st, bool withComments, bool printRanges) {
} }
else st->print("%-20s", ""); else st->print("%-20s", "");
} }
assert(strlen(_name) < 50, "Flag name is longer than expected"); // Make sure we do not punch a '\0' at a negative char array index.
spaces[50 - MAX2((size_t)40, strlen(_name))] = '\0'; unsigned int nameLen = (unsigned int)strlen(_name);
st->print("%s", spaces); if (nameLen <= maxFlagLen) {
spaces[maxFlagLen - MAX2(maxFlagLen-nSpaces, nameLen)] = '\0';
st->print("%s", spaces);
}
print_kind_and_origin(st); print_kind_and_origin(st);
#ifndef PRODUCT #ifndef PRODUCT