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authorChris Wright <chrisw@sous-sol.org>2008-06-04 09:16:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-06-05 14:24:54 -0700
commitddb2c43594f22843e9f3153da151deaba1a834c5 (patch)
tree7eeeca2fa55e9ef45c381b01d9e3ec1b726297c1 /net/ipv4
parentefedf51c866130945b5db755cb58670e60205d83 (diff)
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: Patrick McHardy <kaber@trash.net> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/netfilter/nf_nat_snmp_basic.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/nf_nat_snmp_basic.c b/net/ipv4/netfilter/nf_nat_snmp_basic.c
index 5daefad3d19..7750c97fde7 100644
--- a/net/ipv4/netfilter/nf_nat_snmp_basic.c
+++ b/net/ipv4/netfilter/nf_nat_snmp_basic.c
@@ -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())