In the Linux kernel, the following vulnerability has been resolved: bpf: Fix helper writes to read-only maps Lonial found an issue that despite user- and BPF-side frozen BPF map (like in case of .rodata), it was still possible to write into it from a BPF program side through specific helpers having ARGPTRTO{LONG,INT} as arguments. In checkfuncarg() when the argument is as mentioned, the meta->rawmode is never set. Later, checkhelpermemaccess(), under the case of PTRTOMAPVALUE as register base type, it assumes BPFREAD for the subsequent call to checkmapaccesstype() and given the BPF map is read-only it succeeds. The helpers really need to be annotated as ARGPTRTO{LONG,INT} | MEMUNINIT when results are written into them as opposed to read out of them. The latter indicates that it's okay to pass a pointer to uninitialized memory as the memory is written to anyway. However, ARGPTRTO{LONG,INT} is a special case of ARGPTRTOFIXEDSIZEMEM just with additional alignment requirement. So it is better to just get rid of the ARGPTRTO{LONG,INT} special cases altogether and reuse the fixed size memory types. For this, add MEMALIGNED to additionally ensure alignment given these helpers write directly into the args via <ptr> = val. The .argsize has been initialized reflecting the actual sizeof(*<ptr>). MEMALIGNED can only be used in combination with MEMFIXEDSIZE annotated argument types, since in !MEMFIXEDSIZE cases the verifier does not know the buffer size a priori and therefore cannot blindly write *<ptr> = val.