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path: root/arch/arm/net/bpf_jit_32.c
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Diffstat (limited to 'arch/arm/net/bpf_jit_32.c')
-rw-r--r--arch/arm/net/bpf_jit_32.c42
1 files changed, 39 insertions, 3 deletions
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index e1268f905026..e0e23582c8b4 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -54,6 +54,7 @@
#define SEEN_DATA (1 << (BPF_MEMWORDS + 3))
#define FLAG_NEED_X_RESET (1 << 0)
+#define FLAG_IMM_OVERFLOW (1 << 1)
struct jit_ctx {
const struct bpf_prog *skf;
@@ -293,6 +294,15 @@ static u16 imm_offset(u32 k, struct jit_ctx *ctx)
/* PC in ARM mode == address of the instruction + 8 */
imm = offset - (8 + ctx->idx * 4);
+ if (imm & ~0xfff) {
+ /*
+ * literal pool is too far, signal it into flags. we
+ * can only detect it on the second pass unfortunately.
+ */
+ ctx->flags |= FLAG_IMM_OVERFLOW;
+ return 0;
+ }
+
return imm;
}
@@ -449,10 +459,21 @@ static inline void emit_udiv(u8 rd, u8 rm, u8 rn, struct jit_ctx *ctx)
return;
}
#endif
- if (rm != ARM_R0)
- emit(ARM_MOV_R(ARM_R0, rm), ctx);
+
+ /*
+ * For BPF_ALU | BPF_DIV | BPF_K instructions, rm is ARM_R4
+ * (r_A) and rn is ARM_R0 (r_scratch) so load rn first into
+ * ARM_R1 to avoid accidentally overwriting ARM_R0 with rm
+ * before using it as a source for ARM_R1.
+ *
+ * For BPF_ALU | BPF_DIV | BPF_X rm is ARM_R4 (r_A) and rn is
+ * ARM_R5 (r_X) so there is no particular register overlap
+ * issues.
+ */
if (rn != ARM_R1)
emit(ARM_MOV_R(ARM_R1, rn), ctx);
+ if (rm != ARM_R0)
+ emit(ARM_MOV_R(ARM_R0, rm), ctx);
ctx->seen |= SEEN_CALL;
emit_mov_i(ARM_R3, (u32)jit_udiv, ctx);
@@ -855,6 +876,14 @@ b_epilogue:
default:
return -1;
}
+
+ if (ctx->flags & FLAG_IMM_OVERFLOW)
+ /*
+ * this instruction generated an overflow when
+ * trying to access the literal pool, so
+ * delegate this filter to the kernel interpreter.
+ */
+ return -1;
}
/* compute offsets only during the first pass */
@@ -917,7 +946,14 @@ void bpf_jit_compile(struct bpf_prog *fp)
ctx.idx = 0;
build_prologue(&ctx);
- build_body(&ctx);
+ if (build_body(&ctx) < 0) {
+#if __LINUX_ARM_ARCH__ < 7
+ if (ctx.imm_count)
+ kfree(ctx.imms);
+#endif
+ bpf_jit_binary_free(header);
+ goto out;
+ }
build_epilogue(&ctx);
flush_icache_range((u32)ctx.target, (u32)(ctx.target + ctx.idx));