From 670ef7b2900b38792c357b2db0fadf2881d3d239 Mon Sep 17 00:00:00 2001 From: Daniel Xu Date: Tue, 14 Jan 2025 13:28:43 -0700 Subject: [PATCH] bpf: tcp: Mark bpf_load_hdr_opt() arg2 as read-write [ Upstream commit 8ac412a3361173e3000b16167af3d1f6f90af613 ] 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: 6fad274f06f0 ("bpf: Add MEM_WRITE attribute") Acked-by: Martin KaFai Lau Signed-off-by: Daniel Xu Link: https://lore.kernel.org/r/730e45f8c39be2a5f3d8c4406cceca9d574cbf14.1736886479.git.dxu@dxuuu.xyz Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- net/core/filter.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/filter.c b/net/core/filter.c index 5881944f1681..84992279f4b1 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7604,7 +7604,7 @@ 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, };