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Security issues due to signal handlers

[date: 2018-04-14]

Signal handlers are a good source of bugs.

Delivering Signals for Fun and Profit

Things to look for:

Shared handler touching global data. The signal handling itself is not atomic, since you can hit it with another signal.
grep for "seteuid(0)"; deliver a well-timed signal to run a signal handler with elevated privs.
SIGURG can be delivered over the network.

Timing / side-channel attacks