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authorKees Cook <keescook@chromium.org>2021-09-28 16:09:45 -0700
committerAlexei Starovoitov <ast@kernel.org>2021-09-28 16:27:18 -0700
commit3d717fad5081b8e3bda76d86907fad95398cbde8 (patch)
tree83cb8783224851a17ade5775f15f873f2617586a /lib
parent09710d82c0a3469eadc32781721ac2336fdf915d (diff)
downloadlinux-3d717fad5081b8e3bda76d86907fad95398cbde8.tar.bz2
bpf: Replace "want address" users of BPF_CAST_CALL with BPF_CALL_IMM
In order to keep ahead of cases in the kernel where Control Flow Integrity (CFI) may trip over function call casts, enabling -Wcast-function-type is helpful. To that end, BPF_CAST_CALL causes various warnings and is one of the last places in the kernel triggering this warning. Most places using BPF_CAST_CALL actually just want a void * to perform math on. It's not actually performing a call, so just use a different helper to get the void *, by way of the new BPF_CALL_IMM() helper, which can clean up a common copy/paste idiom as well. This change results in no object code difference. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://github.com/KSPP/linux/issues/20 Link: https://lore.kernel.org/lkml/CAEf4Bzb46=-J5Fxc3mMZ8JQPtK1uoE0q6+g6WPz53Cvx=CBEhw@mail.gmail.com Link: https://lore.kernel.org/bpf/20210928230946.4062144-2-keescook@chromium.org
Diffstat (limited to 'lib')
-rw-r--r--lib/test_bpf.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 08f438e6fe9e..21ea1ab253a1 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -12439,7 +12439,7 @@ static __init int prepare_tail_call_tests(struct bpf_array **pprogs)
err = -EFAULT;
goto out_err;
}
- *insn = BPF_EMIT_CALL(BPF_CAST_CALL(addr));
+ *insn = BPF_EMIT_CALL(addr);
if ((long)__bpf_call_base + insn->imm != addr)
*insn = BPF_JMP_A(0); /* Skip: NOP */
break;