Messages in this thread | | | Date | Mon, 6 Apr 2020 11:55:39 +0200 (CEST) | From | Miroslav Benes <> | Subject | Re: [PATCH] module: Harden STRICT_MODULE_RWX |
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On Fri, 3 Apr 2020, Josh Poimboeuf wrote:
> On Fri, Apr 03, 2020 at 06:37:16PM +0200, Peter Zijlstra wrote: > > +{ > > + int i; > > + > > + for (i = 0; i < hdr->e_shnum; i++) { > > + if (sechdrs[i].sh_flags & (SHF_EXECINSTR|SHF_WRITE)) > > + return -ENOEXEC; > > I think you only want the error when both are set? > > if (sechdrs[i].sh_flags & (SHF_EXECINSTR|SHF_WRITE) == (SHF_EXECINSTR|SHF_WRITE))
A section with SHF_EXECINSTR and SHF_WRITE but without SHF_ALLOC would be strange though, no? It wouldn't be copied to the final module later anyway.
Looking at layout_sections()... a section with SHF_EXECINSTR|SHF_WRITE|SHF_ALLOC would not be counted at all. However, move_module() later copies everything with SHF_ALLOC flag to the final module. If there is WXA section, there would be a bug because the allocation there would not get the correct size. In that case it is important to error out early as you're proposing.
Am I missing something?
Miroslav
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