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4188373020
We were doing stack and syscall-origin region validations before taking the big process lock. There was a window of time where those regions could then be unmapped/remapped by another thread before we proceed with our syscall. This patch closes that window, and makes sys$get_stack_bounds() rely on the fact that we now know the userspace stack pointer to be valid. Thanks to @BenWiederhake for spotting this! :^)
51 lines
2.1 KiB
C++
51 lines
2.1 KiB
C++
/*
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* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <Kernel/Panic.h>
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#include <Kernel/Process.h>
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#include <Kernel/VM/Region.h>
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namespace Kernel {
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int Process::sys$get_stack_bounds(FlatPtr* user_stack_base, size_t* user_stack_size)
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{
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FlatPtr stack_pointer = Thread::current()->get_register_dump_from_stack().userspace_esp;
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auto* stack_region = space().find_region_containing(Range { VirtualAddress(stack_pointer), 1 });
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// The syscall handler should have killed us if we had an invalid stack pointer.
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ASSERT(stack_region);
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FlatPtr stack_base = stack_region->range().base().get();
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size_t stack_size = stack_region->size();
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if (!copy_to_user(user_stack_base, &stack_base))
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return -EFAULT;
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if (!copy_to_user(user_stack_size, &stack_size))
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return -EFAULT;
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return 0;
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}
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}
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