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Commit fdac1e06 authored by Dan Rosenberg's avatar Dan Rosenberg Committed by David S. Miller
Browse files

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: default avatarDan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1bde5ac4

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;