On Fri, Oct 25, 2024 at 10:14:04PM -0700, Rong Xu wrote: > In the presence of both weak and strong function definitions, the > linker drops the weak symbol in favor of a strong symbol, but > leaves the code in place. Code in ignore_unreachable_insn() has > some heuristics to suppress the warning, but it does not work when > -ffunction-sections is enabled. > > Suppose function foo has both strong and weak definitions. > Case 1: The strong definition has an annotated section name, > like .init.text. Only the weak definition will be placed into > .text.foo. But since the section has no symbols, there will be no > "hole" in the section. > > Case 2: Both sections are without an annotated section name. > Both will be placed into .text.foo section, but there will be only one > symbol (the strong one). If the weak code is before the strong code, > there is no "hole" as it fails to find the right-most symbol before > the offset. > > The fix is to use the first node to compute the hole if hole.sym > is empty. If there is no symbol in the section, the first node > will be NULL, in which case, -1 is returned to skip the whole > section. > > Co-developed-by: Han Shen <shenhan@xxxxxxxxxx> > Signed-off-by: Han Shen <shenhan@xxxxxxxxxx> This seems logically correct to me, but I'd love to see review from Josh and/or Peter Z on this change too. Reviewed-by: Kees Cook <kees@xxxxxxxxxx> -- Kees Cook
