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tint: Fix CFI error in BlockAllocator 

Use a memcpy to avoid a bad-cast seat belt which is firing in ChomeOS.

Bug: dawn:1406
Change-Id: I3acf0e2552ef8c5267e8c5701cc2f95f6e283c7a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/89020
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
This commit is contained in:
Ben Clayton 2022-05-05 14:19:20 +00:00 committed by Dawn LUCI CQ
parent f20a867d2f
commit 26cba1cb39
1 changed files with 9 additions and 1 deletions
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10
src/tint/utils/block_allocator.h
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@ -16,6 +16,7 @@
#define SRC_TINT_UTILS_BLOCK_ALLOCATOR_H_ #define SRC_TINT_UTILS_BLOCK_ALLOCATOR_H_
#include <array> #include <array>
#include <cstring>
#include <utility> #include <utility>
#include "src/tint/utils/math.h" #include "src/tint/utils/math.h"
@ -230,7 +231,14 @@ class BlockAllocator {
} }
auto* base = &block_.current->data[0]; auto* base = &block_.current->data[0];
auto* ptr = reinterpret_cast<TYPE*>(base + block_.current_offset); auto* addr = static_cast<void*>(base + block_.current_offset);
// Use a memcpy to reinterpret 'void* addr' as 'TYPE* ptr'.
// This is done without using a static_cast, as Clang's Control Flow Integrity checks can
// trigger for this cast, as we're casting from uint8_t* to TYPE*.
// See: crbug.com/dawn/1406
// See: https://clang.llvm.org/docs/ControlFlowIntegrity.html#bad-cast-checking
TYPE* ptr;
memcpy(&ptr, &addr, sizeof(addr));
block_.current_offset += sizeof(TYPE); block_.current_offset += sizeof(TYPE);
return ptr; return ptr;
} }