fix: guard RemoteAddr parsing against out-of-bounds slice panic - #2463
Merged
alexandre-daubois merged 1 commit intoJun 26, 2026
Merged
Conversation
dunglas
approved these changes
Jun 4, 2026
henderkes
approved these changes
Jun 4, 2026
addKnownVariablesToServer stripped IPv6 brackets with an unchecked slice (ip[1:len(ip)-1]). A malformed RemoteAddr such as "[" or "[:9000" produced a 1-byte ip and panicked. This runs inside the go_register_server_variables cgo callback, where a Go panic cannot unwind through the C frame and aborts the whole process rather than failing a single request. Extract splitRemoteAddr, which parses via net.SplitHostPort and falls back to a bounds-safe lenient split that only strips brackets when both are present. Behavior for well-formed addresses is unchanged.
alexandre-daubois
force-pushed
the
fix/remote-addr-panic-cgo-crash
branch
from
June 26, 2026 07:23
af82b22 to
b98e434
Compare
Member
|
Thanks @iliaal! |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
addKnownVariablesToServerstripped IPv6 brackets with an unchecked slice, so a malformedRemoteAddrlike"["or"[:9000"panicked. This runs in thego_register_server_variablescgo callback, where a panic can't cross the C frame and crashes the whole process. Not reachable behind stock Caddy; reachable for library callers and real-IP rewrites.Fix: parse via
net.SplitHostPortwith a bounds-safe fallback.TestSplitRemoteAddrcovers the crashing inputs; well-formed addresses are unchanged.