fix: addSibling double-free when text merging via last sibling#263
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fix: addSibling double-free when text merging via last sibling#263toddr-bot wants to merge 1 commit into
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xmlAddSibling navigates to parent->last before checking for text merges. The old code only checked self->type, so when self was not a text node but parent->last was, libxml2 merged and freed nNode without the proxy being disconnected — use-after-free / double-free. Replace the two-branch predict-and-copy approach with the same ret != nNode detection pattern used by addChild: save the proxy before calling xmlAddSibling, then NULL it out if the node was consumed by a merge. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
addSiblinghad incomplete text-merge detection: it only checked whetherselfwas a text node, butxmlAddSiblingactually navigates toself->parent->lastbefore merging. Whenselfwas not text but the last sibling was, libxml2 merged and freednNodewithout the proxy being disconnected — causing a use-after-free / double-free.Replaced the two-branch predict-and-copy approach with the same
ret != nNodedetection pattern used byaddChild: save the proxy before callingxmlAddSibling, then NULL it out if the node was consumed by a merge. This handles all merge cases regardless of which sibling triggers the merge.Fixes #246
Changes
addSiblingmerge handling to followaddChild's proven patternaddSiblingcalls with text nodes on a non-text element)Test plan
t/04node.treproduces the double-free scenario from the issueGenerated by Kōan /fix
Quality Report
Changes: 2 files changed, 41 insertions(+), 27 deletions(-)
Code scan: clean
Tests: passed (OK)
Branch hygiene: clean
Generated by Kōan post-mission quality pipeline