From fdac1e0697356ac212259f2147aa60c72e334861 Mon Sep 17 00:00:00 2001 From: Dan Rosenberg Date: Wed, 22 Dec 2010 13:58:27 +0000 Subject: 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 --- net/irda/af_irda.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) (limited to 'net/irda') 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; -- cgit v1.2.3-59-g8ed1b