avoid string table duplicates and DT_NEEDED reference corruption when using --replace-needed multiple times #237
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pranavkapoor001
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* Turns out patchelf (from version 0.9 - 0.10) has trouble working with '--replace-needed' option (see NixOS/patchelf#237), as it corrupted the goodix lib we just patched from extract-utils. * Though I'm still not sure as to why it's seemingly working with few binaries and straight out corrupting others. * Since the host patchelf "seems" to be working just fine, revert back to using it. Signed-off-by: Saurabh Charde <[email protected]>
Swamoy14
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* Turns out patchelf (from version 0.9 - 0.10) has trouble working with '--replace-needed' option (see NixOS/patchelf#237), as it corrupted the goodix lib we just patched from extract-utils. * Though I'm still not sure as to why it's seemingly working with few binaries and straight out corrupting others. * Since the host patchelf "seems" to be working just fine, revert back to using it. Signed-off-by: Saurabh Charde <[email protected]>
When it happens that the .gnu.version_r stores the strings in .dynstr it can come to corruption of the library names written into DT_NEEDED: -the library names in DT_NEEDED are replaced, new entries are written to the end of .dynstr -the version library names are replaced, and written to the end of the string section. If the section for the version strings is also ".dynstr", the previous modifications were _not_ taken into account and things were written from the old end of .dynstr again. The order in which these strings were written is not the same as the previous replacement, so things would end up with the same size, but different offsets. The .gnu.version_r table is correct, the file contents are fine, but the offsets in the DT_NEEDED entries are wrong. Since they are printed as 0-terminated strings the first one replaced will always be shown correct, which also is the case if the argument is only used once as the string is replaced with itself afterwards.
This can happen especially if .gnu.version_r stores the strings in .dynstr, so replacing the library names would add them twice to the same section. Keep a map of what was already added and where, and simply reuse the old entries if they are needed again.
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Thanks! I rebased and merged this. |
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When it happens that the .gnu.version_r stores the strings in .dynstr it can come to corruption of the library names written into DT_NEEDED (#158):
If the section for the version strings is also ".dynstr", the previous modifications were not taken into account and things were written from the old end of .dynstr again. The order in which these strings were written is not the same as the previous replacement, so things would end up with the same size, but different offsets. The .gnu.version_r table is correct, the file contents are fine, but the offsets in the DT_NEEDED entries are wrong. Since they are printed as 0-terminated strings the first one replaced will always be shown correct, which also is the case if the argument is only used once as the string is replaced with itself afterwards.
Now things are correct, but the strings are added to .dynstr twice. Use an unordered map to cache them.