Merge: bpf: tcp: Mark bpf_load_hdr_opt() arg2 as read-write

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/346

JIRA: https://issues.redhat.com/browse/RHEL-78209

    commit 8ac412a
    Author: Daniel Xu <dxu@dxuuu.xyz>
    Date:   Tue Jan 14 13:28:43 2025 -0700

        bpf: tcp: Mark bpf_load_hdr_opt() arg2 as read-write

        MEM_WRITE attribute is defined as: "Non-presence of MEM_WRITE means that
        MEM is only being read". bpf_load_hdr_opt() both reads and writes from
        its arg2 - void *search_res.

        This matters a lot for the next commit where we more precisely track
        stack accesses. Without this annotation, the verifier will make false
        assumptions about the contents of memory written to by helpers and
        possibly prune valid branches.

        Fixes: 6fad274 ("bpf: Add MEM_WRITE attribute")
        Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
        Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
        Link: https://lore.kernel.org/r/730e45f8c39be2a5f3d8c4406cceca9d574cbf14.1736886479.git.dxu@dxuuu.xyz
        Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Signed-off-by: Viktor Malik <vmalik@redhat.com>

Approved-by: Tomas Glozar <tglozar@redhat.com>
Approved-by: Jerome Marchand <jmarchan@redhat.com>
Approved-by: Toke Høiland-Jørgensen <toke@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Jan Stancek <jstancek@redhat.com>

Author: jstancek

net/core/filter.c

@@ -7639,7 +7639,7 @@ static const struct bpf_func_proto bpf_sock_ops_load_hdr_opt_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_WRITE,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 };