tetragon: fix hang on error in tetragonExecute #1770
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There has been a longstanding bug where if Tetragon encounters an error inside of tetragonExecute, the process will hang instead of exiting as expected. When looking at the goroutine stacktrace dump provided by the runtime on SIGABRT, we can immediately see the problem. The main thread is stuck on a channel send inside of observer.RemoveSensors(). Further investigation reveals that the channel is never opened because InitSensorManager() is waiting on the waitChan to be closed, which does not happen until we have loaded the base sensor. To fix this issue, we simply need to move the defer call into observer.RemoveSensors() to after we indicate that InitSensorManager() is cleared to run. This patch does exactly that. Since we haven't loaded any BPF progs yet until the base sensor has been loaded anyway, this should be safe to do. Signed-off-by: William Findlay <will@isovalent.com>
willfindlay
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tpapagian
approved these changes
Nov 17, 2023
kkourt
approved these changes
Nov 17, 2023
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There has been a longstanding bug where if Tetragon encounters an error inside of tetragonExecute, the process will hang instead of exiting as expected. When looking at the goroutine stacktrace dump provided by the runtime on SIGABRT, we can immediately see the problem. The main thread is stuck on a channel send inside of observer.RemoveSensors(). Further investigation reveals that the channel is never opened because InitSensorManager() is waiting on the waitChan to be closed, which does not happen until we have loaded the base sensor.
To fix this issue, we simply need to move the defer call into observer.RemoveSensors() to after we indicate that InitSensorManager() is cleared to run. This patch does exactly that. Since we haven't loaded any BPF progs yet until the base sensor has been loaded anyway, this should be safe to do.