Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2021-09-28

The following pull-request contains BPF updates for your *net* tree.

We've added 10 non-merge commits during the last 14 day(s) which contain
a total of 11 files changed, 139 insertions(+), 53 deletions(-).

The main changes are:

1) Fix MIPS JIT jump code emission for too large offsets, from Piotr Krysiuk.

2) Fix x86 JIT atomic/fetch emission when dst reg maps to rax, from Johan Almbladh.

3) Fix cgroup_sk_alloc corner case when called from interrupt, from Daniel Borkmann.

4) Fix segfault in libbpf's linker for objects without BTF, from Kumar Kartikeya Dwivedi.

5) Fix bpf_jit_charge_modmem for applications with CAP_BPF, from Lorenz Bauer.

6) Fix return value handling for struct_ops BPF programs, from Hou Tao.

7) Various fixes to BPF selftests, from Jiri Benc.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
,

1 files changed, 43 insertions, 14 deletions

diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
index 0af88622c619..cb6d22439f71 100644
--- a/arch/mips/net/bpf_jit.c
+++ b/arch/mips/net/bpf_jit.c
@@ -662,6 +662,11 @@ static void build_epilogue(struct jit_ctx *ctx)
 	((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative : func) : \
 	 func##_positive)
 
+static bool is_bad_offset(int b_off)
+{
+	return b_off > 0x1ffff || b_off < -0x20000;
+}
+
 static int build_body(struct jit_ctx *ctx)
 {
 	const struct bpf_prog *prog = ctx->skf;
@@ -728,7 +733,10 @@ load_common:
 			/* Load return register on DS for failures */
 			emit_reg_move(r_ret, r_zero, ctx);
 			/* Return with error */
-			emit_b(b_imm(prog->len, ctx), ctx);
+			b_off = b_imm(prog->len, ctx);
+			if (is_bad_offset(b_off))
+				return -E2BIG;
+			emit_b(b_off, ctx);
 			emit_nop(ctx);
 			break;
 		case BPF_LD | BPF_W | BPF_IND:
@@ -775,8 +783,10 @@ load_ind:
 			emit_jalr(MIPS_R_RA, r_s0, ctx);
 			emit_reg_move(MIPS_R_A0, r_skb, ctx); /* delay slot */
 			/* Check the error value */
-			emit_bcond(MIPS_COND_NE, r_ret, 0,
-				   b_imm(prog->len, ctx), ctx);
+			b_off = b_imm(prog->len, ctx);
+			if (is_bad_offset(b_off))
+				return -E2BIG;
+			emit_bcond(MIPS_COND_NE, r_ret, 0, b_off, ctx);
 			emit_reg_move(r_ret, r_zero, ctx);
 			/* We are good */
 			/* X <- P[1:K] & 0xf */
@@ -855,8 +865,10 @@ load_ind:
 			/* A /= X */
 			ctx->flags |= SEEN_X | SEEN_A;
 			/* Check if r_X is zero */
-			emit_bcond(MIPS_COND_EQ, r_X, r_zero,
-				   b_imm(prog->len, ctx), ctx);
+			b_off = b_imm(prog->len, ctx);
+			if (is_bad_offset(b_off))
+				return -E2BIG;
+			emit_bcond(MIPS_COND_EQ, r_X, r_zero, b_off, ctx);
 			emit_load_imm(r_ret, 0, ctx); /* delay slot */
 			emit_div(r_A, r_X, ctx);
 			break;
@@ -864,8 +876,10 @@ load_ind:
 			/* A %= X */
 			ctx->flags |= SEEN_X | SEEN_A;
 			/* Check if r_X is zero */
-			emit_bcond(MIPS_COND_EQ, r_X, r_zero,
-				   b_imm(prog->len, ctx), ctx);
+			b_off = b_imm(prog->len, ctx);
+			if (is_bad_offset(b_off))
+				return -E2BIG;
+			emit_bcond(MIPS_COND_EQ, r_X, r_zero, b_off, ctx);
 			emit_load_imm(r_ret, 0, ctx); /* delay slot */
 			emit_mod(r_A, r_X, ctx);
 			break;
@@ -926,7 +940,10 @@ load_ind:
 			break;
 		case BPF_JMP | BPF_JA:
 			/* pc += K */
-			emit_b(b_imm(i + k + 1, ctx), ctx);
+			b_off = b_imm(i + k + 1, ctx);
+			if (is_bad_offset(b_off))
+				return -E2BIG;
+			emit_b(b_off, ctx);
 			emit_nop(ctx);
 			break;
 		case BPF_JMP | BPF_JEQ | BPF_K:
@@ -1056,12 +1073,16 @@ jmp_cmp:
 			break;
 		case BPF_RET | BPF_A:
 			ctx->flags |= SEEN_A;
-			if (i != prog->len - 1)
+			if (i != prog->len - 1) {
 				/*
 				 * If this is not the last instruction
 				 * then jump to the epilogue
 				 */
-				emit_b(b_imm(prog->len, ctx), ctx);
+				b_off = b_imm(prog->len, ctx);
+				if (is_bad_offset(b_off))
+					return -E2BIG;
+				emit_b(b_off, ctx);
+			}
 			emit_reg_move(r_ret, r_A, ctx); /* delay slot */
 			break;
 		case BPF_RET | BPF_K:
@@ -1075,7 +1096,10 @@ jmp_cmp:
 				 * If this is not the last instruction
 				 * then jump to the epilogue
 				 */
-				emit_b(b_imm(prog->len, ctx), ctx);
+				b_off = b_imm(prog->len, ctx);
+				if (is_bad_offset(b_off))
+					return -E2BIG;
+				emit_b(b_off, ctx);
 				emit_nop(ctx);
 			}
 			break;
@@ -1133,8 +1157,10 @@ jmp_cmp:
 			/* Load *dev pointer */
 			emit_load_ptr(r_s0, r_skb, off, ctx);
 			/* error (0) in the delay slot */
-			emit_bcond(MIPS_COND_EQ, r_s0, r_zero,
-				   b_imm(prog->len, ctx), ctx);
+			b_off = b_imm(prog->len, ctx);
+			if (is_bad_offset(b_off))
+				return -E2BIG;
+			emit_bcond(MIPS_COND_EQ, r_s0, r_zero, b_off, ctx);
 			emit_reg_move(r_ret, r_zero, ctx);
 			if (code == (BPF_ANC | SKF_AD_IFINDEX)) {
 				BUILD_BUG_ON(sizeof_field(struct net_device, ifindex) != 4);
@@ -1244,7 +1270,10 @@ void bpf_jit_compile(struct bpf_prog *fp)
 
 	/* Generate the actual JIT code */
 	build_prologue(&ctx);
-	build_body(&ctx);
+	if (build_body(&ctx)) {
+		module_memfree(ctx.target);
+		goto out;
+	}
 	build_epilogue(&ctx);
 
 	/* Update the icache */