6.1-stable review patch. If anyone has any objections, please let me know.
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From: Daniel Xu dxu@dxuuu.xyz
[ 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 martin.lau@kernel.org Signed-off-by: Daniel Xu dxu@dxuuu.xyz Link: https://lore.kernel.org/r/730e45f8c39be2a5f3d8c4406cceca9d574cbf14.173688647... Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 b35615c469e27..370f61f9bf4ba 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7529,7 +7529,7 @@ 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, };