stdbuf: refuse a libstdbuf path that cannot be represented in LD_PRELOAD - #13622
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sylvestre wants to merge 1 commit into
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stdbuf: refuse a libstdbuf path that cannot be represented in LD_PRELOAD#13622sylvestre wants to merge 1 commit into
sylvestre wants to merge 1 commit into
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LD_PRELOAD is colon-separated with no escaping, so a path containing ':' gets split by the loader and its leading component loaded as a library. That path comes from $TMPDIR, so the component is attacker-chosen whenever TMPDIR crosses a privilege boundary (e.g. sudoers env_keep preserving TMPDIR while stripping LD_PRELOAD). With a directory named `payload.so:x` as TMPDIR, an attacker .so runs in the child before main(). GNU is unaffected: it uses a fixed path. Fail with exit 125 instead of preloading a library we did not select.
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LD_PRELOAD is colon-separated with no escaping, so a path containing ':' gets split by the loader and its leading component loaded as a library. That path comes from $TMPDIR, so the component is attacker-chosen whenever TMPDIR crosses a privilege boundary (e.g. sudoers env_keep preserving TMPDIR while stripping LD_PRELOAD). With a directory named
payload.so:xas TMPDIR, an attacker .so runs in the child before main(). GNU is unaffected: it uses a fixed path.Fail with exit 125 instead of preloading a library we did not select.