Merge tag 'v4.20-rc6' into for-4.21/block

Pull in v4.20-rc6 to resolve the conflict in NVMe, but also to get the
two corruption fixes. We're going to be overhauling the direct dispatch
path, and we need to do that on top of the changes we made for that
in mainline.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 89 insertions, 14 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6dd419550aba..fc760d00a38c 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -175,6 +175,7 @@ struct bpf_verifier_stack_elem {
 
 #define BPF_COMPLEXITY_LIMIT_INSNS	131072
 #define BPF_COMPLEXITY_LIMIT_STACK	1024
+#define BPF_COMPLEXITY_LIMIT_STATES	64
 
 #define BPF_MAP_PTR_UNPRIV	1UL
 #define BPF_MAP_PTR_POISON	((void *)((0xeB9FUL << 1) +	\
@@ -3751,6 +3752,79 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
 	}
 }
 
+/* compute branch direction of the expression "if (reg opcode val) goto target;"
+ * and return:
+ *  1 - branch will be taken and "goto target" will be executed
+ *  0 - branch will not be taken and fall-through to next insn
+ * -1 - unknown. Example: "if (reg < 5)" is unknown when register value range [0,10]
+ */
+static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode)
+{
+	if (__is_pointer_value(false, reg))
+		return -1;
+
+	switch (opcode) {
+	case BPF_JEQ:
+		if (tnum_is_const(reg->var_off))
+			return !!tnum_equals_const(reg->var_off, val);
+		break;
+	case BPF_JNE:
+		if (tnum_is_const(reg->var_off))
+			return !tnum_equals_const(reg->var_off, val);
+		break;
+	case BPF_JGT:
+		if (reg->umin_value > val)
+			return 1;
+		else if (reg->umax_value <= val)
+			return 0;
+		break;
+	case BPF_JSGT:
+		if (reg->smin_value > (s64)val)
+			return 1;
+		else if (reg->smax_value < (s64)val)
+			return 0;
+		break;
+	case BPF_JLT:
+		if (reg->umax_value < val)
+			return 1;
+		else if (reg->umin_value >= val)
+			return 0;
+		break;
+	case BPF_JSLT:
+		if (reg->smax_value < (s64)val)
+			return 1;
+		else if (reg->smin_value >= (s64)val)
+			return 0;
+		break;
+	case BPF_JGE:
+		if (reg->umin_value >= val)
+			return 1;
+		else if (reg->umax_value < val)
+			return 0;
+		break;
+	case BPF_JSGE:
+		if (reg->smin_value >= (s64)val)
+			return 1;
+		else if (reg->smax_value < (s64)val)
+			return 0;
+		break;
+	case BPF_JLE:
+		if (reg->umax_value <= val)
+			return 1;
+		else if (reg->umin_value > val)
+			return 0;
+		break;
+	case BPF_JSLE:
+		if (reg->smax_value <= (s64)val)
+			return 1;
+		else if (reg->smin_value > (s64)val)
+			return 0;
+		break;
+	}
+
+	return -1;
+}
+
 /* Adjusts the register min/max values in the case that the dst_reg is the
  * variable register that we are working on, and src_reg is a constant or we're
  * simply doing a BPF_K check.
@@ -4152,21 +4226,15 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
 
 	dst_reg = &regs[insn->dst_reg];
 
-	/* detect if R == 0 where R was initialized to zero earlier */
-	if (BPF_SRC(insn->code) == BPF_K &&
-	    (opcode == BPF_JEQ || opcode == BPF_JNE) &&
-	    dst_reg->type == SCALAR_VALUE &&
-	    tnum_is_const(dst_reg->var_off)) {
-		if ((opcode == BPF_JEQ && dst_reg->var_off.value == insn->imm) ||
-		    (opcode == BPF_JNE && dst_reg->var_off.value != insn->imm)) {
-			/* if (imm == imm) goto pc+off;
-			 * only follow the goto, ignore fall-through
-			 */
+	if (BPF_SRC(insn->code) == BPF_K) {
+		int pred = is_branch_taken(dst_reg, insn->imm, opcode);
+
+		if (pred == 1) {
+			 /* only follow the goto, ignore fall-through */
 			*insn_idx += insn->off;
 			return 0;
-		} else {
-			/* if (imm != imm) goto pc+off;
-			 * only follow fall-through branch, since
+		} else if (pred == 0) {
+			/* only follow fall-through branch, since
 			 * that's where the program will go
 			 */
 			return 0;
@@ -4980,7 +5048,7 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 	struct bpf_verifier_state_list *new_sl;
 	struct bpf_verifier_state_list *sl;
 	struct bpf_verifier_state *cur = env->cur_state, *new;
-	int i, j, err;
+	int i, j, err, states_cnt = 0;
 
 	sl = env->explored_states[insn_idx];
 	if (!sl)
@@ -5007,8 +5075,12 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 			return 1;
 		}
 		sl = sl->next;
+		states_cnt++;
 	}
 
+	if (!env->allow_ptr_leaks && states_cnt > BPF_COMPLEXITY_LIMIT_STATES)
+		return 0;
+
 	/* there were no equivalent states, remember current one.
 	 * technically the current state is not proven to be safe yet,
 	 * but it will either reach outer most bpf_exit (which means it's safe)
@@ -5148,6 +5220,9 @@ static int do_check(struct bpf_verifier_env *env)
 			goto process_bpf_exit;
 		}
 
+		if (signal_pending(current))
+			return -EAGAIN;
+
 		if (need_resched())
 			cond_resched();