From: Dan Rosenberg Date: Wed, 22 Dec 2010 13:58:27 +0000 (+0000) Subject: irda: prevent integer underflow in IRLMP_ENUMDEVICES X-Git-Tag: v2.6.27.59~17 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=621eff477de5b98ca070752231a470dd3e2fce5a;p=thirdparty%2Fkernel%2Fstable.git irda: prevent integer underflow in IRLMP_ENUMDEVICES commit fdac1e0697356ac212259f2147aa60c72e334861 upstream. 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 Cc: Moritz Muehlenhoff Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/irda/af_irda.c b/net/irda/af_irda.c index b28409cf3fa0e..e71364bdcb73a 100644 --- a/net/irda/af_irda.c +++ b/net/irda/af_irda.c @@ -2165,6 +2165,14 @@ 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) + return -EINVAL; + /* Ask lmp for the current discovery log */ discoveries = irlmp_get_discoveries(&list.len, self->mask.word, self->nslots); @@ -2174,15 +2182,9 @@ static int irda_getsockopt(struct socket *sock, int level, int optname, err = 0; /* 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) {