Date: Mon, 28 Nov 2022 20:47:40 +0100 From: Markus Wichmann <nullplan@....net> To: musl@...ts.openwall.com Subject: Invalid page size reference in __dls2 Hi all, __dls2 calls kernel_mapped_dso(), and that one uses the PAGE_SIZE macro. Whenever <bits/limits.h> does not define PAGESIZE, PAGE_SIZE is defined as libc.page_size. That variable is only initialized at the start of __dls3, so the DSO descriptor for libc ends up being wrong. Since the libc object has static storage duration, page_size is initialized with zero. So at least nothing undefined happens. The impact is, it will calculate the relro pointers as being zero, so no relro will happen, and it will calculate maximum and minimum addresses as being zero, therefore setting map to base and map_len to zero. This will cause dladdr() not to find the libc. Yeah, not the biggest of impacts. This, again, affects all architectures that don't define PAGESIZE, so at this time those are aarch64 arm m68k microblaze mips mips64 mipsn32 powerpc powerpc64 riscv64 I don't know whether references to libc are even valid in __dls2, but it is defined as "hidden", so that ought to be good enough. In that case it may be enough to just move the initialization. Otherwise it may be necessary to add page size as parameter to kernel_mapped_dso(). Then __dls2 can look it up in the aux vector at its leisure. Ciao, Markus
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