Merge tag 'v4.4.177' into toradex_vf_4.4-nextColibri-VF_LXDE-Image_2.8b6.183-20190331

This is the 4.4.177 stable release

1 files changed, 77 insertions, 21 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 35dfa9e9d69e..c43ca9857479 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -191,6 +191,7 @@ struct bpf_insn_aux_data {
 		enum bpf_reg_type ptr_type;	/* pointer type for load/store insns */
 		struct bpf_map *map_ptr;	/* pointer for call insn into lookup_elem */
 	};
+	int sanitize_stack_off; /* stack slot to be cleared */
 	bool seen; /* this insn was processed by the verifier */
 };
 
@@ -569,10 +570,11 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
 /* check_stack_read/write functions track spill/fill of registers,
  * stack boundary and alignment are checked in check_mem_access()
  */
-static int check_stack_write(struct verifier_state *state, int off, int size,
-			     int value_regno)
+static int check_stack_write(struct verifier_env *env,
+			     struct verifier_state *state, int off,
+			     int size, int value_regno, int insn_idx)
 {
-	int i;
+	int i, spi = (MAX_BPF_STACK + off) / BPF_REG_SIZE;
 	/* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
 	 * so it's aligned access and [off, off + size) are within stack limits
 	 */
@@ -587,15 +589,37 @@ static int check_stack_write(struct verifier_state *state, int off, int size,
 		}
 
 		/* save register state */
-		state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
-			state->regs[value_regno];
-
-		for (i = 0; i < BPF_REG_SIZE; i++)
+		state->spilled_regs[spi] = state->regs[value_regno];
+
+		for (i = 0; i < BPF_REG_SIZE; i++) {
+			if (state->stack_slot_type[MAX_BPF_STACK + off + i] == STACK_MISC &&
+			    !env->allow_ptr_leaks) {
+				int *poff = &env->insn_aux_data[insn_idx].sanitize_stack_off;
+				int soff = (-spi - 1) * BPF_REG_SIZE;
+
+				/* detected reuse of integer stack slot with a pointer
+				 * which means either llvm is reusing stack slot or
+				 * an attacker is trying to exploit CVE-2018-3639
+				 * (speculative store bypass)
+				 * Have to sanitize that slot with preemptive
+				 * store of zero.
+				 */
+				if (*poff && *poff != soff) {
+					/* disallow programs where single insn stores
+					 * into two different stack slots, since verifier
+					 * cannot sanitize them
+					 */
+					verbose("insn %d cannot access two stack slots fp%d and fp%d",
+						insn_idx, *poff, soff);
+					return -EINVAL;
+				}
+				*poff = soff;
+			}
 			state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL;
+		}
 	} else {
 		/* regular write of data into stack */
-		state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
-			(struct reg_state) {};
+		state->spilled_regs[spi] = (struct reg_state) {};
 
 		for (i = 0; i < size; i++)
 			state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;
@@ -696,7 +720,7 @@ static bool is_ctx_reg(struct verifier_env *env, int regno)
  * if t==write && value_regno==-1, some unknown value is stored into memory
  * if t==read && value_regno==-1, don't care what we read from memory
  */
-static int check_mem_access(struct verifier_env *env, u32 regno, int off,
+static int check_mem_access(struct verifier_env *env, int insn_idx, u32 regno, int off,
 			    int bpf_size, enum bpf_access_type t,
 			    int value_regno)
 {
@@ -748,7 +772,8 @@ static int check_mem_access(struct verifier_env *env, u32 regno, int off,
 				verbose("attempt to corrupt spilled pointer on stack\n");
 				return -EACCES;
 			}
-			err = check_stack_write(state, off, size, value_regno);
+			err = check_stack_write(env, state, off, size,
+						value_regno, insn_idx);
 		} else {
 			err = check_stack_read(state, off, size, value_regno);
 		}
@@ -760,7 +785,7 @@ static int check_mem_access(struct verifier_env *env, u32 regno, int off,
 	return err;
 }
 
-static int check_xadd(struct verifier_env *env, struct bpf_insn *insn)
+static int check_xadd(struct verifier_env *env, int insn_idx, struct bpf_insn *insn)
 {
 	struct reg_state *regs = env->cur_state.regs;
 	int err;
@@ -793,13 +818,13 @@ static int check_xadd(struct verifier_env *env, struct bpf_insn *insn)
 	}
 
 	/* check whether atomic_add can read the memory */
-	err = check_mem_access(env, insn->dst_reg, insn->off,
+	err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
 			       BPF_SIZE(insn->code), BPF_READ, -1);
 	if (err)
 		return err;
 
 	/* check whether atomic_add can write into the same memory */
-	return check_mem_access(env, insn->dst_reg, insn->off,
+	return check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
 				BPF_SIZE(insn->code), BPF_WRITE, -1);
 }
 
@@ -1838,13 +1863,14 @@ static int do_check(struct verifier_env *env)
 			/* check that memory (src_reg + off) is readable,
 			 * the state of dst_reg will be updated by this func
 			 */
-			err = check_mem_access(env, insn->src_reg, insn->off,
+			err = check_mem_access(env, insn_idx, insn->src_reg, insn->off,
 					       BPF_SIZE(insn->code), BPF_READ,
 					       insn->dst_reg);
 			if (err)
 				return err;
 
-			if (BPF_SIZE(insn->code) != BPF_W) {
+			if (BPF_SIZE(insn->code) != BPF_W &&
+			    BPF_SIZE(insn->code) != BPF_DW) {
 				insn_idx++;
 				continue;
 			}
@@ -1876,7 +1902,7 @@ static int do_check(struct verifier_env *env)
 			enum bpf_reg_type *prev_dst_type, dst_reg_type;
 
 			if (BPF_MODE(insn->code) == BPF_XADD) {
-				err = check_xadd(env, insn);
+				err = check_xadd(env, insn_idx, insn);
 				if (err)
 					return err;
 				insn_idx++;
@@ -1895,7 +1921,7 @@ static int do_check(struct verifier_env *env)
 			dst_reg_type = regs[insn->dst_reg].type;
 
 			/* check that memory (dst_reg + off) is writeable */
-			err = check_mem_access(env, insn->dst_reg, insn->off,
+			err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
 					       BPF_SIZE(insn->code), BPF_WRITE,
 					       insn->src_reg);
 			if (err)
@@ -1930,7 +1956,7 @@ static int do_check(struct verifier_env *env)
 			}
 
 			/* check that memory (dst_reg + off) is writeable */
-			err = check_mem_access(env, insn->dst_reg, insn->off,
+			err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
 					       BPF_SIZE(insn->code), BPF_WRITE,
 					       -1);
 			if (err)
@@ -2220,13 +2246,43 @@ static int convert_ctx_accesses(struct verifier_env *env)
 	for (i = 0; i < insn_cnt; i++, insn++) {
 		u32 cnt;
 
-		if (insn->code == (BPF_LDX | BPF_MEM | BPF_W))
+		if (insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
+		    insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
 			type = BPF_READ;
-		else if (insn->code == (BPF_STX | BPF_MEM | BPF_W))
+		else if (insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
+			 insn->code == (BPF_STX | BPF_MEM | BPF_DW))
 			type = BPF_WRITE;
 		else
 			continue;
 
+		if (type == BPF_WRITE &&
+		    env->insn_aux_data[i + delta].sanitize_stack_off) {
+			struct bpf_insn patch[] = {
+				/* Sanitize suspicious stack slot with zero.
+				 * There are no memory dependencies for this store,
+				 * since it's only using frame pointer and immediate
+				 * constant of zero
+				 */
+				BPF_ST_MEM(BPF_DW, BPF_REG_FP,
+					   env->insn_aux_data[i + delta].sanitize_stack_off,
+					   0),
+				/* the original STX instruction will immediately
+				 * overwrite the same stack slot with appropriate value
+				 */
+				*insn,
+			};
+
+			cnt = ARRAY_SIZE(patch);
+			new_prog = bpf_patch_insn_data(env, i + delta, patch, cnt);
+			if (!new_prog)
+				return -ENOMEM;
+
+			delta    += cnt - 1;
+			env->prog = new_prog;
+			insn      = new_prog->insnsi + i + delta;
+			continue;
+		}
+
 		if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX)
 			continue;