irda: prevent integer underflow in IRLMP_ENUMDEVICES

PATCH Applied Dan Rosenberg 2 participants 2 messages Dec 22, 2010 – Dec 23, 2010

Subsystems (2)

Networking Network drivers

lore

Share & tools

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Dan Rosenberg

author

2010-12-22 23:58 UTC #0 lore raw

PATCH 1/1 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 <[email protected]>

Cc stable <[email protected]>

---
 net/irda/af_irda.c |   18 +++++++++++-------
 1 files changed, 11 insertions(+), 7 deletions(-)

net/irda/af_irda.c +11 -7

index a6de305..241d7a0 100644
@@ -2280,6 +2280,16 @@ 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);

@@ -2290,15 +2300,9 @@ 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;

David Miller

maintainer Applied

2010-12-23 18:08 UTC #1 lore raw

From: Dan Rosenberg <[email protected]>
Date: Wed, 22 Dec 2010 18:58:27 -0500

Quoted 7 lines

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 <[email protected]>

Applied, thanks.