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Kernel: Disallow syscalls from writeable memory

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Processes will now crash with SIGSEGV if they attempt making a syscall
from PROT_WRITE memory.

This neat idea comes from OpenBSD. :^)
This commit is contained in:
Andreas Kling 2019-11-29 16:15:30 +01:00
parent ea52fe528a
commit e56daf547c
5 changed files with 27 additions and 5 deletions
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13
Kernel/Syscall.cpp
View file

@ -105,6 +105,19 @@ void syscall_trap_entry(RegisterDump regs)
ASSERT_NOT_REACHED();
}
auto* calling_region = MM.region_from_vaddr(process, VirtualAddress(regs.eip));
if (!calling_region) {
dbgprintf("Syscall from %p which has no region\n", regs.eip);
handle_crash(regs, "Syscall from unknown region", SIGSEGV);
ASSERT_NOT_REACHED();
}
if (calling_region->is_writable()) {
dbgprintf("Syscall from writable memory at %p\n", regs.eip);
handle_crash(regs, "Syscall from writable memory", SIGSEGV);
ASSERT_NOT_REACHED();
}
process.big_lock().lock();
u32 function = regs.eax;
u32 arg1 = regs.edx;