`write` and similar calls allows reading from allocated but protected memory.

[trungnt2910]

    const int size = 4096;
    void* ptr = mmap(nullptr, size, PROT_NONE, MAP_ANON | MAP_PRIVATE, -1, 0);
    // Crashes
    // std::cout << "Pointer value is: " << std::flush << *(int*)ptr << std::endl;
    // Still returns 1, expected -1
    std::cout << write(fds[1], ptr, 1) << std::endl;
    // false, expected true
    std::cout << std::boolalpha << (errno == EFAULT) << std::noboolalpha << std::endl;

Some portable libraries targeting POSIX is using the write function and write to a dummy pipe to check if a range of memory is accessible.

For non-accessible memory (either unallocated or protected), the function should return -1 and set errno to EFAULT .

On Haiku, this works well for unallocated memory, but not for protected memory. Therefore, the code snippet above doesn't run as expected.

The full code is attached to this ticket.

[trungnt2910]

Minimal C++ program for testing this bug

[waddlesplash]

Fix merged in hrev56131. Thanks for working on this!

[kim1963]

Reopened.

ркум56131 - no boot !!!!!!!!!!!!!!!!!!!!!!!!!!

[korli]

We might well revert and only apply first the changes in the drivers and go from there.

[waddlesplash]

At least one KDL, in SATA/AHCI, was already reported via IRC. I will fix that today, it's possible whatever kim1963 is seeing is the same. New tickets should be opened however, not reopening old ones.