Hi Ken, On Jan 18 15:58, Ken Brown wrote: > Hi Corinna, > > I'm puzzled by the code at mmap.cc:1294 starting with if (!in_mapped). If we > get there and in_mapped is false, then the pages in the mprotect call don't > meet any mmap_record. Why do we continue after that? Is there some case > where a user program would expect mprotect to succeed on pages that were not > mapped by mmap? There must be some subtlety involving PAGE_WRITECOPY that > I'm missing.
Nothing like that. This is following Linux, see the mprotect manpage: [...] VERSIONS POSIX says that the behavior of mprotect() is unspecified if it is ap‐ plied to a region of memory that was not obtained via mmap(2). On Linux, it is always permissible to call mprotect() on any address in a process's address space (except for the kernel vsyscall area). In particular, it can be used to change existing code mappings to be writable. [...] Corinna
