On Thu, May 21, 2020 at 04:50:32AM +0200, Jann Horn wrote: > On Tue, May 19, 2020 at 7:38 AM Andrii Nakryiko <andriin@xxxxxx> wrote: > > As discussed in [0], it's dangerous to allow mapping BPF map, that's meant to > > be frozen and is read-only on BPF program side, because that allows user-space > > to actually store a writable view to the page even after it is frozen. This is > > exacerbated by BPF verifier making a strong assumption that contents of such > > frozen map will remain unchanged. To prevent this, disallow mapping > > BPF_F_RDONLY_PROG mmap()'able BPF maps as writable, ever. > > > > [0] https://lore.kernel.org/bpf/CAEf4BzYGWYhXdp6BJ7_=9OQPJxQpgug080MMjdSB72i9R+5c6g@xxxxxxxxxxxxxx/ > > > > Suggested-by: Jann Horn <jannh@xxxxxxxxxx> > > Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY") > > Signed-off-by: Andrii Nakryiko <andriin@xxxxxx> > > Reviewed-by: Jann Horn <jannh@xxxxxxxxxx> I fixed trailing white space after 'writable page' and applied to bpf tree. Thanks
