1. mmap all memory always, without explicit mmap calls in the program.
This makes lots of things much easier and removes lots of code.
Makes mmap not a special syscall and allows to fuzz without mmap enabled.
2. Change address assignment algorithm.
Current algorithm allocates unmapped addresses too frequently
and allows collisions between arguments of a single syscall.
The new algorithm analyzes actual allocations in the program
and places new arguments at unused locations.
Make Foreach* callback accept the arg and a context struct
that can contain lots of aux info.
This (1) removes lots of unuser base/parent args,
(2) provides foundation for stopping recursion,
(3) allows to merge foreachSubargOffset.
Now each prog function accepts the desired target explicitly.
No global, implicit state involved.
This is much cleaner and allows cross-OS/arch testing, etc.
Large overhaul moves syscalls and arg types from sys to prog.
Sys package now depends on prog and contains only generated
descriptions of syscalls.
Introduce prog.Target type that encapsulates all targer properties,
like syscall list, ptr/page size, etc. Also moves OS-dependent pieces
like mmap call generation from prog to sys.
Update #191
We currently use uintptr for all values.
This won't work for 32-bit archs.
Moreover in some cases we use uintptr but assume
that it is always 64-bits (e.g. in encodingexec).
Switch everything to uint64.
Update #324
Right now Arg is a huge struct (160 bytes), which has many different fields
used for different arg kinds. Since most of the args we see in a typical
corpus are ArgConst, this results in a significant memory overuse.
This change:
- makes Arg an interface instead of a struct
- adds a SomethingArg struct for each arg kind we have
- converts all *Arg pointers into just Arg, since interface variable by
itself contains a pointer to the actual data
- removes ArgPageSize, now ConstArg is used instead
- consolidates correspondence between arg kinds and types, see comments
before each SomethingArg struct definition
- now LenType args that denote the length of VmaType args are serialized as
"0x1000" instead of "(0x1000)"; to preserve backwards compatibility
syzkaller is able to parse the old format for now
- multiple small changes all over to make the above work
After this change syzkaller uses twice less memory after deserializing a
typical corpus.
