upstream commit 3832ba4e283d7052b783dab8311df7e3590fed93

Add checks to ensure that we never emit branch instructions with truncated branch offsets.

Suggested-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Naveen N. Rao naveen.n.rao@linux.vnet.ibm.com Tested-by: Johan Almbladh johan.almbladh@anyfinetworks.com Reviewed-by: Christophe Leroy christophe.leroy@csgroup.eu Acked-by: Song Liu songliubraving@fb.com Acked-by: Johan Almbladh johan.almbladh@anyfinetworks.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/71d33a6b7603ec1013c9734dd8bdd4ff5e929142.163346414... [expand is_offset_in_[cond_]branch_range() helpers, drop ppc32 changes] Signed-off-by: Naveen N. Rao naveen.n.rao@linux.vnet.ibm.com --- arch/powerpc/net/bpf_jit.h | 25 +++++++++++++++++++------ arch/powerpc/net/bpf_jit_comp64.c | 10 +++++++--- 2 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index 83e5b255d1423e..89e61b109c17fa 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h @@ -177,13 +177,26 @@ #define PPC_NEG(d, a) EMIT(PPC_INST_NEG | ___PPC_RT(d) | ___PPC_RA(a))

/* Long jump; (unconditional 'branch') */ -#define PPC_JMP(dest) EMIT(PPC_INST_BRANCH | \ - (((dest) - (ctx->idx * 4)) & 0x03fffffc)) +#define PPC_JMP(dest) \ + do { \ + long offset = (long)(dest) - (ctx->idx * 4); \ + if (offset < -0x2000000 || offset > 0x1fffffc || offset & 0x3) { \ + pr_err_ratelimited("Branch offset 0x%lx (@%u) out of range\n", offset, ctx->idx); \ + return -ERANGE; \ + } \ + EMIT(PPC_INST_BRANCH | (offset & 0x03fffffc)); \ + } while (0) /* "cond" here covers BO:BI fields. */ -#define PPC_BCC_SHORT(cond, dest) EMIT(PPC_INST_BRANCH_COND | \ - (((cond) & 0x3ff) << 16) | \ - (((dest) - (ctx->idx * 4)) & \ - 0xfffc)) +#define PPC_BCC_SHORT(cond, dest) \ + do { \ + long offset = (long)(dest) - (ctx->idx * 4); \ + if (offset < -0x8000 || offset > 0x7fff || offset & 0x3) { \ + pr_err_ratelimited("Conditional branch offset 0x%lx (@%u) out of range\n", offset, ctx->idx); \ + return -ERANGE; \ + } \ + EMIT(PPC_INST_BRANCH_COND | (((cond) & 0x3ff) << 16) | (offset & 0xfffc)); \ + } while (0) + /* Sign-extended 32-bit immediate load */ #define PPC_LI32(d, i) do { \ if ((int)(uintptr_t)(i) >= -32768 && \ diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index e08e55cd98e6f5..3f867e79dfaa75 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -239,7 +239,7 @@ static void bpf_jit_emit_func_call(u32 *image, struct codegen_context *ctx, u64 PPC_BLRL(); }

-static void bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out) +static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out) { /* * By now, the eBPF program has already setup parameters in r3, r4 and r5 @@ -300,7 +300,9 @@ static void bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 bpf_jit_emit_common_epilogue(image, ctx);

PPC_BCTR(); + /* out: */ + return 0; }

/* Assemble the body code between the prologue & epilogue */ @@ -310,7 +312,7 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, { const struct bpf_insn *insn = fp->insnsi; int flen = fp->len; - int i; + int i, ret;

/* Start of epilogue code - will only be valid 2nd pass onwards */ u32 exit_addr = addrs[flen]; @@ -938,7 +940,9 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, */ case BPF_JMP | BPF_CALL | BPF_X: ctx->seen |= SEEN_TAILCALL; - bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]); + ret = bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]); + if (ret < 0) + return ret; break;

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