From: Dan Rosenberg Date: Wed, 22 Dec 2010 13:58:27 +0000 (+0000) Subject: irda: prevent integer underflow in IRLMP_ENUMDEVICES X-Git-Tag: v2.6.37-rc8~13^2~5 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fdac1e0697356ac212259f2147aa60c72e334861;p=pandora-kernel.git irda: prevent integer underflow in IRLMP_ENUMDEVICES If the user-provided len is less than the expected offset, the IRLMP_ENUMDEVICES getsockopt will do a copy_to_user() with a very large size value. While this isn't be a security issue on x86 because it will get caught by the access_ok() check, it may leak large amounts of kernel heap on other architectures. In any event, this patch fixes it. Signed-off-by: Dan Rosenberg Signed-off-by: David S. Miller --- diff --git a/net/irda/af_irda.c b/net/irda/af_irda.c index 7f097989cde2..5007541b6478 100644 --- a/net/irda/af_irda.c +++ b/net/irda/af_irda.c @@ -2281,6 +2281,16 @@ static int irda_getsockopt(struct socket *sock, int level, int optname, switch (optname) { case IRLMP_ENUMDEVICES: + + /* Offset to first device entry */ + offset = sizeof(struct irda_device_list) - + sizeof(struct irda_device_info); + + if (len < offset) { + err = -EINVAL; + goto out; + } + /* Ask lmp for the current discovery log */ discoveries = irlmp_get_discoveries(&list.len, self->mask.word, self->nslots); @@ -2291,15 +2301,9 @@ static int irda_getsockopt(struct socket *sock, int level, int optname, } /* Write total list length back to client */ - if (copy_to_user(optval, &list, - sizeof(struct irda_device_list) - - sizeof(struct irda_device_info))) + if (copy_to_user(optval, &list, offset)) err = -EFAULT; - /* Offset to first device entry */ - offset = sizeof(struct irda_device_list) - - sizeof(struct irda_device_info); - /* Copy the list itself - watch for overflow */ if (list.len > 2048) { err = -EINVAL;