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Kernel: Fix kernel null deref on process crash during join_thread()

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The join_thread() syscall is not supposed to be interruptible by
signals, but it was. And since the process death mechanism piggybacked
on signal interrupts, it was possible to interrupt a pthread_join() by
killing the process that was doing it, leading to confusing due to some
assumptions being made by Thread::finalize() for threads that have a
pending joiner.

This patch fixes the issue by making "interrupted by death" a distinct
block result separate from "interrupted by signal". Then we handle that
state in join_thread() and tidy things up so that thread finalization
doesn't get confused by the pending joiner being gone.

Test: Tests/Kernel/null-deref-crash-during-pthread_join.cpp
This commit is contained in:
Andreas Kling 2020-01-10 19:15:01 +01:00
parent 6a529ea425
commit 8c5cd97b45
7 changed files with 55 additions and 20 deletions
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4
Kernel/Net/IPv4Socket.cpp
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@ -240,7 +240,7 @@ ssize_t IPv4Socket::recvfrom(FileDescription& description, void* buffer, size_t
LOCKER(lock());
if (!m_can_read) {
if (res == Thread::BlockResult::InterruptedBySignal)
if (res != Thread::BlockResult::WokeNormally)
return -EINTR;
// Unblocked due to timeout.
@ -288,7 +288,7 @@ ssize_t IPv4Socket::recvfrom(FileDescription& description, void* buffer, size_t
LOCKER(lock());
if (!m_can_read) {
if (res == Thread::BlockResult::InterruptedBySignal)
if (res != Thread::BlockResult::WokeNormally)
return -EINTR;
// Unblocked due to timeout.