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Kernel+LibC: Make page fault crashes a bit more readable.

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We'll now try to detect crashes that were due to dereferencing nullptr,
uninitialized malloc() memory, or recently free()'d memory.
It's not perfect but I think it's pretty good. :^)

Also added some color to the most important parts of the crash log,
and added some more modes to /bin/crash for exercising this code.

Fixes #243.
This commit is contained in:
Andreas Kling 2019-06-19 20:52:12 +02:00
parent 15bea7153a
commit 8c0ae711d8
5 changed files with 76 additions and 11 deletions
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43
Userland/crash.cpp
View file

@ -4,17 +4,22 @@
static void print_usage_and_exit()
{
printf("usage: crash -[sdia]\n");
printf("usage: crash -[sdiamfMF]\n");
exit(0);
}
#pragma GCC optimize("O0")
int main(int argc, char** argv)
{
enum Mode {
SegmentationViolation,
DivisionByZero,
IllegalInstruction,
Abort
Abort,
WriteToUninitializedMallocMemory,
WriteToFreedMemory,
ReadFromUninitializedMallocMemory,
ReadFromFreedMemory,
};
Mode mode = SegmentationViolation;
@ -29,6 +34,14 @@ int main(int argc, char** argv)
mode = IllegalInstruction;
else if (String(argv[1]) == "-a")
mode = Abort;
else if (String(argv[1]) == "-m")
mode = ReadFromUninitializedMallocMemory;
else if (String(argv[1]) == "-f")
mode = ReadFromFreedMemory;
else if (String(argv[1]) == "-M")
mode = WriteToUninitializedMallocMemory;
else if (String(argv[1]) == "-F")
mode = WriteToFreedMemory;
else
print_usage_and_exit();
@ -55,6 +68,32 @@ int main(int argc, char** argv)
ASSERT_NOT_REACHED();
}
if (mode == ReadFromUninitializedMallocMemory) {
auto* uninitialized_memory = (volatile dword**)malloc(1024);
volatile auto x = uninitialized_memory[0][0];
ASSERT_NOT_REACHED();
}
if (mode == ReadFromFreedMemory) {
auto* uninitialized_memory = (volatile dword**)malloc(1024);
free(uninitialized_memory);
volatile auto x = uninitialized_memory[4][0];
ASSERT_NOT_REACHED();
}
if (mode == WriteToUninitializedMallocMemory) {
auto* uninitialized_memory = (volatile dword**)malloc(1024);
uninitialized_memory[4][0] = 1;
ASSERT_NOT_REACHED();
}
if (mode == WriteToFreedMemory) {
auto* uninitialized_memory = (volatile dword**)malloc(1024);
free(uninitialized_memory);
uninitialized_memory[4][0] = 1;
ASSERT_NOT_REACHED();
}
ASSERT_NOT_REACHED();
return 0;
}