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Commit 5e1f5420 authored by Neal Cardwell's avatar Neal Cardwell Committed by David S. Miller
Browse files

inet_diag: validate port comparison byte code to prevent unsafe reads 



Add logic to verify that a port comparison byte code operation
actually has the second inet_diag_bc_op from which we read the port
for such operations.

Previously the code blindly referenced op[1] without first checking
whether a second inet_diag_bc_op struct could fit there. So a
malicious user could make the kernel read 4 bytes beyond the end of
the bytecode array by claiming to have a whole port comparison byte
code (2 inet_diag_bc_op structs) when in fact the bytecode was not
long enough to hold both.

Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f67caec9

net/ipv4/inet_diag.c

+24 −7
Original line number Original line Diff line number Diff line
@@ -557,6 +557,17 @@ static bool valid_hostcond(const struct inet_diag_bc_op *op, int len, 
	return true;

	return true;

}

}





/* Validate a port comparison operator. */

static inline bool valid_port_comparison(const struct inet_diag_bc_op *op,

					 int len, int *min_len)

{

	/* Port comparisons put the port in a follow-on inet_diag_bc_op. */

	*min_len += sizeof(struct inet_diag_bc_op);

	if (len < *min_len)

		return false;

	return true;

}



static int inet_diag_bc_audit(const void *bytecode, int bytecode_len)

static int inet_diag_bc_audit(const void *bytecode, int bytecode_len)

{

{

	const void *bc = bytecode;

	const void *bc = bytecode;
@@ -572,24 +583,30 @@ static int inet_diag_bc_audit(const void *bytecode, int bytecode_len) 
		case INET_DIAG_BC_D_COND:

		case INET_DIAG_BC_D_COND:

			if (!valid_hostcond(bc, len, &min_len))

			if (!valid_hostcond(bc, len, &min_len))

				return -EINVAL;

				return -EINVAL;

			/* fall through */

			break;

		case INET_DIAG_BC_AUTO:

		case INET_DIAG_BC_S_GE:

		case INET_DIAG_BC_S_GE:

		case INET_DIAG_BC_S_LE:

		case INET_DIAG_BC_S_LE:

		case INET_DIAG_BC_D_GE:

		case INET_DIAG_BC_D_GE:

		case INET_DIAG_BC_D_LE:

		case INET_DIAG_BC_D_LE:

		case INET_DIAG_BC_JMP:

			if (!valid_port_comparison(bc, len, &min_len))

			if (op->no < min_len || op->no > len + 4 || op->no & 3)

				return -EINVAL;

			if (op->no < len &&

			    !valid_cc(bytecode, bytecode_len, len - op->no))

				return -EINVAL;

				return -EINVAL;

			break;

			break;

		case INET_DIAG_BC_AUTO:

		case INET_DIAG_BC_JMP:

		case INET_DIAG_BC_NOP:

		case INET_DIAG_BC_NOP:

			break;

			break;

		default:

		default:

			return -EINVAL;

			return -EINVAL;

		}

		}



		if (op->code != INET_DIAG_BC_NOP) {

			if (op->no < min_len || op->no > len + 4 || op->no & 3)

				return -EINVAL;

			if (op->no < len &&

			    !valid_cc(bytecode, bytecode_len, len - op->no))

				return -EINVAL;

		}



		if (op->yes < min_len || op->yes > len + 4 || op->yes & 3)

		if (op->yes < min_len || op->yes > len + 4 || op->yes & 3)

			return -EINVAL;

			return -EINVAL;

		bc  += op->yes;

		bc  += op->yes;