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Kernel: Mask kernel addresses in backtraces and profiles

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Addresses outside the userspace virtual range will now show up as
0xdeadc0de in backtraces and profiles generated by unprivileged users.
This commit is contained in:
Andreas Kling 2020-01-02 20:49:21 +01:00
parent 8eb20bdfa2
commit 32ec1e5aed
4 changed files with 24 additions and 14 deletions
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6
Kernel/FileSystem/ProcFS.cpp
View file

@ -365,6 +365,7 @@ Optional<KBuffer> procfs$profile(InodeIdentifier)
InterruptDisabler disabler;
KBufferBuilder builder;
JsonArraySerializer array(builder);
bool mask_kernel_addresses = !current->process().is_superuser();
Profiling::for_each_sample([&](auto& sample) {
auto object = array.add_object();
object.add("pid", sample.pid);
@ -375,7 +376,10 @@ Optional<KBuffer> procfs$profile(InodeIdentifier)
if (sample.frames[i] == 0)
break;
auto frame_object = frames_array.add_object();
frame_object.add("address", JsonValue((u32)sample.frames[i]));
u32 address = (u32)sample.frames[i];
if (mask_kernel_addresses && !is_user_address(VirtualAddress(address)))
address = 0xdeadc0de;
frame_object.add("address", address);
frame_object.add("symbol", sample.symbolicated_frames[i]);
frame_object.add("offset", JsonValue((u32)sample.offsets[i]));
frame_object.finish();

22
Kernel/Thread.cpp
View file

@ -714,21 +714,27 @@ String Thread::backtrace_impl() const
recognized_symbols.append({ retaddr, ksymbolicate(retaddr) });
}
bool mask_kernel_addresses = !current->process().is_superuser();
for (auto& symbol : recognized_symbols) {
if (!symbol.address)
break;
if (!symbol.ksym) {
if (!Scheduler::is_active() && process.elf_loader() && process.elf_loader()->has_symbols())
builder.appendf("%p %s\n", symbol.address, process.elf_loader()->symbolicate(symbol.address).characters());
else
builder.appendf("%p\n", symbol.address);
if (!is_user_address(VirtualAddress(symbol.address))) {
builder.append("0xdeadc0de\n");
} else {
if (!Scheduler::is_active() && process.elf_loader() && process.elf_loader()->has_symbols())
builder.appendf("%p %s\n", symbol.address, process.elf_loader()->symbolicate(symbol.address).characters());
else
builder.appendf("%p\n", symbol.address);
}
continue;
}
unsigned offset = symbol.address - symbol.ksym->address;
if (symbol.ksym->address == ksym_highest_address && offset > 4096)
builder.appendf("%p\n", symbol.address);
else
builder.appendf("%p %s +%u\n", symbol.address, demangle(symbol.ksym->name).characters(), offset);
if (symbol.ksym->address == ksym_highest_address && offset > 4096) {
builder.appendf("%p\n", mask_kernel_addresses ? 0xdeadc0de : symbol.address);
} else {
builder.appendf("%p %s +%u\n", mask_kernel_addresses ? 0xdeadc0de : symbol.address, demangle(symbol.ksym->name).characters(), offset);
}
}
return builder.to_string();
}

5
Kernel/VM/MemoryManager.cpp
View file

@ -601,11 +601,6 @@ void MemoryManager::unquickmap_page()
m_quickmap_in_use = false;
}
static inline bool is_user_address(VirtualAddress vaddr)
{
return vaddr.get() >= (8 * MB) && vaddr.get() < 0xc0000000;
}
template<MemoryManager::AccessSpace space, MemoryManager::AccessType access_type>
bool MemoryManager::validate_range(const Process& process, VirtualAddress base_vaddr, size_t size) const
{

5
Kernel/VM/MemoryManager.h
View file

@ -159,3 +159,8 @@ void VMObject::for_each_region(Callback callback)
callback(region);
}
}
inline bool is_user_address(VirtualAddress vaddr)
{
return vaddr.get() >= (8 * MB) && vaddr.get() < 0xc0000000;
}