avoid the possibility of dangling pointers while processing capture items in pcre2_compile #248
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I'm missing something here. I don't see how passing the chain of open_capitems via its own argument is any different to passing it as a member of the compile block structure. The items themselves are still on the stack. Oh, perhaps the idea is to confine this value to the nested compile_{branch,regex} functions? OK, I think I can understand that. In which case, the patch looks straightforward. |
As shown by the following warning from gcc13:
src/pcre2_compile.c: In function 'compile_regex':
src/pcre2_compile.c:8319:17: warning: storing the address of local variable 'capitem' in '*cb.open_caps' [-Wdangling-pointer=]
8319 | cb->open_caps = &capitem;
| ~~~~~~~~~~~~~~^~~~~~~~~~
While normally the stack of "capitems" will be unwinded and the head of
it that is stored in "cb" set to NULL, this is not done in case of a
compilation failure.
Instead of keeping it inside "cb", initialize it in the stack of
compile_regex() and make sure it is gone once that function returns.
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Updated the commit message to hopefully make it clearer. |
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Raised by gcc 13 (from MinGW and Fedora 38):
While cb.open_caps is not needed outside the possibly recursive calls to compile_regex() and compile_branch(), it is safer to not keep it with possibly dangling references once they are out of scope.