Improve error handling of libxml2 calls in xml.c This commit fixes some defects in the backend's xml.c, found upon inspection of the internals of libxml2: - xmlEncodeSpecialChars() can fail on malloc(), returning NULL back to the caller. xmltext() assumed that this could never happen. Like other code paths, a TRY/CATCH block is added there, covering also the fact that cstring_to_text_with_len() could fail a memory allocation, where the backend would miss to free the buffer allocated by xmlEncodeSpecialChars(). - Some libxml2 routines called in xmlelement() can return NULL, like xmlAddChildList() or xmlTextWriterStartElement(). Dedicated errors are added for them. - xml_xmlnodetoxmltype() missed that xmlXPathCastNodeToString() can fail on an allocation failure. In this case, the call can just be moved to the existing TRY/CATCH block.
All these code paths would cause the server to crash. As this is unlikely a problem in practice, no backpatch is done. Jim and I have caught these defects, not sure who has scored the most. The contrib module xml2/ has similar defects, which will be addressed in a separate change. Reported-by: Jim Jones <jim.jo...@uni-muenster.de> Reviewed-by: Jim Jones <jim.jo...@uni-muenster.de> Discussion: https://postgr.es/m/aeeingzota_s_...@paquier.xyz Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/2e947217474c15c7fd9011d1ab2b0d4657b3eae2 Modified Files -------------- src/backend/utils/adt/xml.c | 78 +++++++++++++++++++++++++++++++++++---------- 1 file changed, 62 insertions(+), 16 deletions(-)
