commit 33afb8403f361919aa5c8fe1d0a4f5ddbfbbea3c Author: Chris Wright Date: Wed Jun 4 09:16:33 2008 -0700 asn1: additional sanity checking during BER decoding (CVE-2008-1673) upstream commit: ddb2c43594f22843e9f3153da151deaba1a834c5 - 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 Cc: stable@kernel.org Acked-by: Patrick McHardy Signed-off-by: Chris Wright Signed-off-by: Linus Torvalds fs/cifs/asn1.c | 14 ++++++++++++++ net/ipv4/netfilter/ip_nat_snmp_basic.c | 16 +++++++++++++++- 2 files changed, 29 insertions(+), 1 deletions(-) diff --git a/fs/cifs/asn1.c b/fs/cifs/asn1.c index 2e75883..4b37a68 100644 --- a/fs/cifs/asn1.c +++ b/fs/cifs/asn1.c @@ -182,6 +182,11 @@ 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; } @@ -199,6 +204,10 @@ 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 @@ -385,6 +394,11 @@ 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; diff --git a/net/ipv4/netfilter/ip_nat_snmp_basic.c b/net/ipv4/netfilter/ip_nat_snmp_basic.c index 18b7fbd..b507120 100644 --- a/net/ipv4/netfilter/ip_nat_snmp_basic.c +++ b/net/ipv4/netfilter/ip_nat_snmp_basic.c @@ -235,6 +235,11 @@ 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; } @@ -252,7 +257,11 @@ static unsigned char asn1_header_decode(struct asn1_ctx *ctx, def = len = 0; 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 @@ -437,6 +446,11 @@ 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())