[PATCH bpf-next 5/7] sparc: bpf: Fix off-by-one in tail call count limiting
From: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Date: 2021-08-09 09:35:23
Also in:
bpf
Subsystem:
bpf jit for sparc (32-bit and 64-bit), bpf [general] (safe dynamic programs and tools), sparc + ultrasparc (sparc/sparc64), the rest · Maintainers:
David S. Miller, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Andreas Larsson, Linus Torvalds
Before, the eBPF JIT allowed up to MAX_TAIL_CALL_CNT + 1 tail calls. Now, precisely MAX_TAIL_CALL_CNT is allowed, which is in line with the behaviour of the interpreter. Verified with the test_bpf test suite on qemu-system-sparc64. Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> --- arch/sparc/net/bpf_jit_comp_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/sparc/net/bpf_jit_comp_64.c b/arch/sparc/net/bpf_jit_comp_64.c
index 9a2f20cbd48b..0bfe1c72a0c9 100644
--- a/arch/sparc/net/bpf_jit_comp_64.c
+++ b/arch/sparc/net/bpf_jit_comp_64.c@@ -867,7 +867,7 @@ static void emit_tail_call(struct jit_ctx *ctx) emit(LD32 | IMMED | RS1(SP) | S13(off) | RD(tmp), ctx); emit_cmpi(tmp, MAX_TAIL_CALL_CNT, ctx); #define OFFSET2 13 - emit_branch(BGU, ctx->idx, ctx->idx + OFFSET2, ctx); + emit_branch(BGEU, ctx->idx, ctx->idx + OFFSET2, ctx); emit_nop(ctx); emit_alu_K(ADD, tmp, 1, ctx);
--
2.25.1