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Kernel: Set EFLAGS/RFLAGS to a known-good value on signal entry

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This commit is contained in:
Sergey Lisov
2022-11-21 00:36:24 +03:00
committed by Andreas Kling
parent 839c1a574d
commit 18af8be0e6
1 changed files with 9 additions and 0 deletions
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9
Kernel/Thread.cpp
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@@ -1234,6 +1234,15 @@ DispatchSignalResult Thread::dispatch_signal(u8 signal)
auto signal_trampoline_addr = process.signal_trampoline().get();
regs.set_ip(signal_trampoline_addr);
// Userspace flags might be invalid for function entry, according to SYSV ABI (section 3.2.1).
// Set them to a known-good value to avoid weird handler misbehavior.
// Only IF (and the reserved bit 1) are set.
#if ARCH(I386)
regs.set_flags(2 | (regs.eflags & ~safe_eflags_mask));
#elif ARCH(X86_64)
regs.set_flags(2 | (regs.rflags & ~safe_eflags_mask));
#endif
dbgln_if(SIGNAL_DEBUG, "Thread in state '{}' has been primed with signal handler {:#04x}:{:p} to deliver {}", state_string(), m_regs.cs, m_regs.ip(), signal);
return DispatchSignalResult::Continue;