irda: prevent integer underflow in IRLMP_ENUMDEVICES (fdac1e06) · Commits · 戴 / test

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 <drosenberg@vsecurity.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/irda/af_irda.c

+11 −7

Original line number	Diff line number	Diff line
		@@ -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;

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