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https://github.com/RGBCube/serenity
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4b2651ddab
The way the Process::FileDescriptions::allocate() API works today means that two callers who allocate back to back without associating a FileDescription with the allocated FD, will receive the same FD and thus one will stomp over the other. Naively tracking which FileDescriptions are allocated and moving onto the next would introduce other bugs however, as now if you "allocate" a fd and then return early further down the control flow of the syscall you would leak that fd. This change modifies this behavior by tracking which descriptions are allocated and then having an RAII type to "deallocate" the fd if the association is not setup the end of it's scope.
55 lines
1.5 KiB
C++
55 lines
1.5 KiB
C++
/*
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* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/FileSystem/AnonymousFile.h>
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#include <Kernel/FileSystem/FileDescription.h>
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#include <Kernel/Process.h>
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#include <Kernel/VM/AnonymousVMObject.h>
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namespace Kernel {
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KResultOr<FlatPtr> Process::sys$anon_create(size_t size, int options)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
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REQUIRE_PROMISE(stdio);
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if (!size)
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return EINVAL;
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if (size % PAGE_SIZE)
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return EINVAL;
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if (size > NumericLimits<ssize_t>::max())
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return EINVAL;
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auto new_fd_or_error = m_fds.allocate();
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if (new_fd_or_error.is_error())
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return new_fd_or_error.error();
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auto new_fd = new_fd_or_error.release_value();
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auto vmobject = AnonymousVMObject::try_create_purgeable_with_size(size, AllocationStrategy::Reserve);
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if (!vmobject)
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return ENOMEM;
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auto anon_file = AnonymousFile::create(vmobject.release_nonnull());
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if (!anon_file)
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return ENOMEM;
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auto description_or_error = FileDescription::create(*anon_file);
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if (description_or_error.is_error())
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return description_or_error.error();
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auto description = description_or_error.release_value();
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description->set_writable(true);
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description->set_readable(true);
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u32 fd_flags = 0;
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if (options & O_CLOEXEC)
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fd_flags |= FD_CLOEXEC;
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m_fds[new_fd.fd].set(move(description), fd_flags);
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return new_fd.fd;
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}
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}
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