From: Daniel Xu Date: Tue, 14 Jan 2025 20:28:43 +0000 (-0700) Subject: bpf: tcp: Mark bpf_load_hdr_opt() arg2 as read-write X-Git-Tag: v6.14-rc1~133^2~4^2~3 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8ac412a3361173e3000b16167af3d1f6f90af613;p=thirdparty%2Fkernel%2Flinux.git 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: 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 --- diff --git a/net/core/filter.c b/net/core/filter.c index 21131ec25f24a..713d6f454df3a 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7643,7 +7643,7 @@ 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, };