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executor: protect most of kcov region

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We only write to the first page of kcov region.
Protect the rest from the fuzzer.
This commit is contained in:
Dmitry Vyukov 2018-05-14 15:31:14 +02:00
parent 364ad1502f
commit 9467cacb1c
1 changed files with 4 additions and 2 deletions
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6
executor/executor_linux.cc
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@ -144,11 +144,13 @@ void cover_open()
if (ioctl(th->cover_fd, kcov_init_trace, kCoverSize))
fail("cover init trace write failed");
size_t mmap_alloc_size = kCoverSize * (is_kernel_64_bit ? 8 : 4);
th->cover_data = (char*)mmap(NULL, mmap_alloc_size,
PROT_READ | PROT_WRITE, MAP_SHARED, th->cover_fd, 0);
th->cover_data = (char*)mmap(NULL, mmap_alloc_size, PROT_READ, MAP_SHARED, th->cover_fd, 0);
th->cover_end = th->cover_data + mmap_alloc_size;
if (th->cover_data == MAP_FAILED)
fail("cover mmap failed");
// We only write to the first page, so protect the rest from fuzzer.
if (mprotect(th->cover_data, SYZ_PAGE_SIZE, PROT_READ | PROT_WRITE))
fail("cover mprotect failed");
}
}