inet_diag: fix inet_diag_bc_audit()

A malicious user or buggy application can inject code and trigger an
infinite loop in inet_diag_bc_audit()

Also make sure each instruction is aligned on 4 bytes boundary, to avoid
unaligned accesses.

Reported-by: Dan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 8 deletions

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 6ffe94ca5bc9..3267d3898437 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -437,7 +437,7 @@ static int valid_cc(const void *bc, int len, int cc)
                         return 0;
                 if (cc == len)
                         return 1;
-                if (op->yes < 4)
+                if (op->yes < 4 || op->yes & 3)
                         return 0;
                 len -= op->yes;
                 bc  += op->yes;
@@ -447,11 +447,11 @@ static int valid_cc(const void *bc, int len, int cc)
 
 static int inet_diag_bc_audit(const void *bytecode, int bytecode_len)
 {
-        const unsigned char *bc = bytecode;
+        const void *bc = bytecode;
         int  len = bytecode_len;
 
         while (len > 0) {
-                struct inet_diag_bc_op *op = (struct inet_diag_bc_op *)bc;
+                const struct inet_diag_bc_op *op = bc;
 
 //printk("BC: %d %d %d {%d} / %d\n", op->code, op->yes, op->no, op[1].no, len);
                 switch (op->code) {
@@ -462,22 +462,20 @@ static int inet_diag_bc_audit(const void *bytecode, int bytecode_len)
                 case INET_DIAG_BC_S_LE:
                 case INET_DIAG_BC_D_GE:
                 case INET_DIAG_BC_D_LE:
-                        if (op->yes < 4 || op->yes > len + 4)
-                                return -EINVAL;
                 case INET_DIAG_BC_JMP:
-                        if (op->no < 4 || op->no > len + 4)
+                        if (op->no < 4 || op->no > len + 4 || op->no & 3)
                                 return -EINVAL;
                         if (op->no < len &&
                             !valid_cc(bytecode, bytecode_len, len - op->no))
                                 return -EINVAL;
                         break;
                 case INET_DIAG_BC_NOP:
-                        if (op->yes < 4 || op->yes > len + 4)
-                                return -EINVAL;
                         break;
                 default:
                         return -EINVAL;
                 }
+                if (op->yes < 4 || op->yes > len + 4 || op->yes & 3)
+                        return -EINVAL;
                 bc  += op->yes;
                 len -= op->yes;
         }