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| author | Dmitry Vyukov <dvyukov@google.com> | 2017-01-25 11:01:30 +0100 |
|---|---|---|
| committer | Dmitry Vyukov <dvyukov@google.com> | 2017-01-25 11:01:30 +0100 |
| commit | f810d0844478c385985e2d0fe0a6a603a7b1c8bd (patch) | |
| tree | 6f1c5ff716e3e22d1f3cda7d681d349fd7f659fb /executor/common_kvm_amd64.h | |
| parent | 40723a067e2216f643485b732f90202b38b59e4b (diff) | |
executor: protect against memory corruptions better
Fuzzer has figured out how to corrupt input/output shmem regions
abusing the text memcpy in syz_kvm_setup_cpu. It guessed a negative
text_size value that causes the memcpy to overwrite shmem regions.
Protect better against such cases:
1. Make text_size unsigned (there is already a check that it is less than 1000).
2. Map input region as readable only, we don't write to it.
3. Add address sanity check to segv_handler, if we see that we are writing
into executable data, it's better to crash instantly.
Diffstat (limited to 'executor/common_kvm_amd64.h')
| -rw-r--r-- | executor/common_kvm_amd64.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/executor/common_kvm_amd64.h b/executor/common_kvm_amd64.h index 558026d5c..f5d061bb1 100644 --- a/executor/common_kvm_amd64.h +++ b/executor/common_kvm_amd64.h @@ -287,7 +287,7 @@ static uintptr_t syz_kvm_setup_cpu(uintptr_t a0, uintptr_t a1, uintptr_t a2, uin (void)text_count; // fuzzer can spoof count and we need just 1 text, so ignore text_count int text_type = 0; const void* text = 0; - int text_size = 0; + uintptr_t text_size = 0; NONFAILING(text_type = text_array_ptr[0].typ); NONFAILING(text = text_array_ptr[0].text); NONFAILING(text_size = text_array_ptr[0].size); |