mirrors/serenity
1
0
Fork 0
mirror of https://github.com/SerenityOS/serenity.git synced 2025-01-23 18:02:05 -05:00
Code Issues Projects Releases Packages Wiki Activity

Kernel: Add some basic double-kfree() detection

Browse source 
Double kfree() is exceedingly rare in our kernel since we use automatic
memory management and smart pointers for almost all code. However, it
doesn't hurt to do some basic checking that might one day catch bugs.

This patch makes us VERIFY that we don't already consider the first
chunk of a kmalloc() allocation free when kfree()'ing it.
This commit is contained in:
Andreas Kling 2021-04-09 09:08:23 +02:00
parent fa9f5c9799
commit 79ebcacce2
1 changed files with 4 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
Kernel/Heap/Heap.h
View file

@ -107,9 +107,12 @@ public:
return;
auto* a = (AllocationHeader*)((((u8*)ptr) - sizeof(AllocationHeader)));
VERIFY((u8*)a >= m_chunks && (u8*)ptr < m_chunks + m_total_chunks * CHUNK_SIZE);
VERIFY((u8*)a + a->allocation_size_in_chunks * CHUNK_SIZE <= m_chunks + m_total_chunks * CHUNK_SIZE);
FlatPtr start = ((FlatPtr)a - (FlatPtr)m_chunks) / CHUNK_SIZE;
// First, verify that the start of the allocation at `ptr` is actually allocated.
VERIFY(m_bitmap.get(start));
VERIFY((u8*)a + a->allocation_size_in_chunks * CHUNK_SIZE <= m_chunks + m_total_chunks * CHUNK_SIZE);
m_bitmap.set_range(start, a->allocation_size_in_chunks, false);
VERIFY(m_allocated_chunks >= a->allocation_size_in_chunks);