Commit ddb2c435 authored by Chris Wright's avatar Chris Wright Committed by Linus Torvalds
Browse files

asn1: additional sanity checking during BER decoding 



- Don't trust a length which is greater than the working buffer.
  An invalid length could cause overflow when calculating buffer size
  for decoding oid.

- An oid length of zero is invalid and allows for an off-by-one error when
  decoding oid because the first subid actually encodes first 2 subids.

- A primitive encoding may not have an indefinite length.

Thanks to Wei Wang from McAfee for report.

Cc: Steven French <sfrench@us.ibm.com>
Cc: stable@kernel.org
Acked-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarChris Wright <chrisw@sous-sol.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent efedf51c

fs/cifs/asn1.c

+14 −0
Original line number Diff line number Diff line
@@ -186,6 +186,11 @@ asn1_length_decode(struct asn1_ctx *ctx, unsigned int *def, unsigned int *len) 
			}

		}

	}



	/* don't trust len bigger than ctx buffer */

	if (*len > ctx->end - ctx->pointer)

		return 0;



	return 1;

}
@@ -203,6 +208,10 @@ asn1_header_decode(struct asn1_ctx *ctx, 
	if (!asn1_length_decode(ctx, &def, &len))

		return 0;



	/* primitive shall be definite, indefinite shall be constructed */

	if (*con == ASN1_PRI && !def)

		return 0;



	if (def)

		*eoc = ctx->pointer + len;

	else
@@ -389,6 +398,11 @@ asn1_oid_decode(struct asn1_ctx *ctx, 
	unsigned long *optr;



	size = eoc - ctx->pointer + 1;



	/* first subid actually encodes first two subids */

	if (size < 2 || size > ULONG_MAX/sizeof(unsigned long))

		return 0;



	*oid = kmalloc(size * sizeof(unsigned long), GFP_ATOMIC);

	if (*oid == NULL)

		return 0;

net/ipv4/netfilter/nf_nat_snmp_basic.c

+14 −0
Original line number Diff line number Diff line
@@ -232,6 +232,11 @@ static unsigned char asn1_length_decode(struct asn1_ctx *ctx, 
			}

		}

	}



	/* don't trust len bigger than ctx buffer */

	if (*len > ctx->end - ctx->pointer)

		return 0;



	return 1;

}
@@ -250,6 +255,10 @@ static unsigned char asn1_header_decode(struct asn1_ctx *ctx, 
	if (!asn1_length_decode(ctx, &def, &len))

		return 0;



	/* primitive shall be definite, indefinite shall be constructed */

	if (*con == ASN1_PRI && !def)

		return 0;



	if (def)

		*eoc = ctx->pointer + len;

	else
@@ -434,6 +443,11 @@ static unsigned char asn1_oid_decode(struct asn1_ctx *ctx, 
	unsigned long *optr;



	size = eoc - ctx->pointer + 1;



	/* first subid actually encodes first two subids */

	if (size < 2 || size > ULONG_MAX/sizeof(unsigned long))

		return 0;



	*oid = kmalloc(size * sizeof(unsigned long), GFP_ATOMIC);

	if (*oid == NULL) {

		if (net_ratelimit())

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