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Kernel: Add memory scrubbing in slab_alloc() and slab_dealloc()

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These now scrub allocated and freed memory like kmalloc()/kfree() was
already doing.
This commit is contained in:
Andreas Kling 2020-02-01 10:36:25 +01:00
parent 934b1d8a9b
commit 37d336d741
Notes: sideshowbarker 2024-07-19 09:44:06 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/37d336d7414
3 changed files with 16 additions and 0 deletions
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6
Kernel/Arch/i386/CPU.cpp
View file

@ -319,6 +319,8 @@ void page_fault_handler(RegisterDump regs)
u32 free_scrub_pattern = explode_byte(FREE_SCRUB_BYTE);
u32 kmalloc_scrub_pattern = explode_byte(KMALLOC_SCRUB_BYTE);
u32 kfree_scrub_pattern = explode_byte(KFREE_SCRUB_BYTE);
u32 slab_alloc_scrub_pattern = explode_byte(SLAB_ALLOC_SCRUB_BYTE);
u32 slab_dealloc_scrub_pattern = explode_byte(SLAB_DEALLOC_SCRUB_BYTE);
if ((fault_address & 0xffff0000) == (malloc_scrub_pattern & 0xffff0000)) {
kprintf("\033[33;1mNote: Address %p looks like it may be uninitialized malloc() memory\033[0m\n", fault_address);
} else if ((fault_address & 0xffff0000) == (free_scrub_pattern & 0xffff0000)) {
@ -327,6 +329,10 @@ void page_fault_handler(RegisterDump regs)
kprintf("\033[33;1mNote: Address %p looks like it may be uninitialized kmalloc() memory\033[0m\n", fault_address);
} else if ((fault_address & 0xffff0000) == (kfree_scrub_pattern & 0xffff0000)) {
kprintf("\033[33;1mNote: Address %p looks like it may be recently kfree()'d memory\033[0m\n", fault_address);
} else if ((fault_address & 0xffff0000) == (slab_alloc_scrub_pattern & 0xffff0000)) {
kprintf("\033[33;1mNote: Address %p looks like it may be uninitialized slab_alloc() memory\033[0m\n", fault_address);
} else if ((fault_address & 0xffff0000) == (slab_dealloc_scrub_pattern & 0xffff0000)) {
kprintf("\033[33;1mNote: Address %p looks like it may be recently slab_dealloc()'d memory\033[0m\n", fault_address);
} else if (fault_address < 4096) {
kprintf("\033[33;1mNote: Address %p looks like a possible nullptr dereference\033[0m\n", fault_address);
}

7
Kernel/Heap/SlabAllocator.cpp
View file

@ -61,6 +61,9 @@ public:
m_freelist = m_freelist->next;
++m_num_allocated;
--m_num_free;
#ifdef SANITIZE_KMALLOC
memset(ptr, SLAB_ALLOC_SCRUB_BYTE, slab_size());
#endif
return ptr;
}
@ -73,6 +76,10 @@ public:
return;
}
((FreeSlab*)ptr)->next = m_freelist;
#ifdef SANITIZE_KMALLOC
if (slab_size() > sizeof(FreeSlab*))
memset(((FreeSlab*)ptr)->padding, SLAB_DEALLOC_SCRUB_BYTE, sizeof(FreeSlab::padding));
#endif
m_freelist = (FreeSlab*)ptr;
++m_num_allocated;
--m_num_free;

3
Kernel/Heap/SlabAllocator.h
View file

@ -29,6 +29,9 @@
#include <AK/Function.h>
#include <AK/Types.h>
#define SLAB_ALLOC_SCRUB_BYTE 0xab
#define SLAB_DEALLOC_SCRUB_BYTE 0xbc
class JsonObjectSerializer;
void* slab_alloc(size_t slab_size);