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>

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 6ffe94c..3267d38 100644 (file)
--- 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;
        }