GHSA-gmq2-39ff-f5qg A failed upgrade may lead to hung goroutines
A failed upgrade in the tableflip library can cause hung goroutines in the parent process, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Not stated
- Victim action needed
- Not needed
- Fix
- Available
What is GHSA-gmq2-39ff-f5qg?
GHSA-gmq2-39ff-f5qg is a denial of service vulnerability in github.com/cloudflare/tableflip, published on 21 May 2021.
Official description
Impact
Processes using tableflip may encounter hung goroutines in the parent process, after a failed upgrade.
The Go runtime has annoying behaviour around setting and clearing O_NONBLOCK: exec.Cmd.Start() ends up calling os.File.Fd() for any file in exec.Cmd.ExtraFiles. os.File.Fd() disables both the use of the runtime poller for the file and clears O_NONBLOCK from the underlying open file descriptor.
This can lead to goroutines hanging in a parent process, after at least one failed upgrade. The bug manifests in goroutines which rely on either a deadline or interruption via Close() to be unblocked being stuck in read or accept like syscalls. As far as I can tell we've not experienced this problem in production, so it's most likely quite rare.
Patches
The problem has been fixed in v1.2.2.
Workarounds
None.
References
Which versions are affected by GHSA-gmq2-39ff-f5qg?
2 open source packages ship an affected version, including github.com/cloudflare/tableflip.
| Package | Affected | Fixed in |
|---|---|---|
github.com/cloudflare/tableflip Go | All versions | 1.2.2 |
github.com/cloudflare/tableflip Go | All versions | 1.2.2 |
How do I fix GHSA-gmq2-39ff-f5qg?
Upgrade github.com/cloudflare/tableflip to 1.2.2 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is GHSA-gmq2-39ff-f5qg being exploited?
There is no known exploitation of GHSA-gmq2-39ff-f5qg in the wild and no public exploit code.