From: Daniel Borkmann daniel@iogearbox.net
commit eb1b66887472eaa7342305b7890ae510dd9d1a79 upstream.
Convert the bpf_probe_write_user() helper to probe_user_write() such that writes are not attempted under KERNEL_DS anymore which is buggy as kernel and user space pointers can have overlapping addresses. Also, given we have the access_ok() check inside probe_user_write(), the helper doesn't need to do it twice.
Fixes: 96ae52279594 ("bpf: Add bpf_probe_write_user BPF helper to be called in tracers") Signed-off-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Alexei Starovoitov ast@kernel.org Acked-by: Andrii Nakryiko andriin@fb.com Link: https://lore.kernel.org/bpf/841c461781874c07a0ee404a454c3bc0459eed30.1572649... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/trace/bpf_trace.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
--- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -163,7 +163,7 @@ static const struct bpf_func_proto bpf_p .arg3_type = ARG_ANYTHING, };
-BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src, +BPF_CALL_3(bpf_probe_write_user, void __user *, unsafe_ptr, const void *, src, u32, size) { /* @@ -186,10 +186,8 @@ BPF_CALL_3(bpf_probe_write_user, void *, return -EPERM; if (unlikely(!nmi_uaccess_okay())) return -EPERM; - if (!access_ok(unsafe_ptr, size)) - return -EPERM;
- return probe_kernel_write(unsafe_ptr, src, size); + return probe_user_write(unsafe_ptr, src, size); }
static const struct bpf_func_proto bpf_probe_write_user_proto = {