CVE-2022-49341CVE-2022-49341

In the Linux kernel, the following vulnerability has been resolved: bpf, arm64: Clear prog->jited_len along prog->jited syzbot reported an illegal copy_to_user() attempt from bpf_prog_get_info_by_fd() [1] There was no repro yet on this bug, but I think that commit 0aef499f3172 ("mm/usercopy: Detect vmalloc overruns") is exposing a prior bug in bpf arm64. bpf_prog_get_info_by_fd() looks at prog->jited_len to determine if the JIT image can be copied out to user space. My theory is that syzbot managed to get a prog where prog->jited_len has been set to 43, while prog->bpf_func has ben cleared. It is not clear why copy_to_user(uinsns, NULL, ulen) is triggering this particular warning. I thought find_vma_area(NULL) would not find a vm_struct. As we do not hold vmap_area_lock spinlock, it might be possible that the found vm_struct was garbage. [1] usercopy: Kernel memory exposure attempt detected from vmalloc (offset 792633534417210172, size 43)! kernel BUG at mm/usercopy.c:101! Inte