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irda: prevent integer underflow in IRLMP_ENUMDEVICES

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commit fdac1e0697 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 <drosenberg@vsecurity.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Moritz Muehlenhoff <jmm@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Dan Rosenberg
2010-12-22 13:58:27 +00:00
committed by Greg Kroah-Hartman
parent 7847ca8cdb
commit 9d880cedb1
1 changed files with 9 additions and 7 deletions
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16
net/irda/af_irda.c
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@@ -2164,6 +2164,14 @@ 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);
@@ -2173,15 +2181,9 @@ 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)
{