| From | Paul Gortmaker <> | Subject | [34-longterm 236/247] irda: prevent integer underflow in IRLMP_ENUMDEVICES | Date | Thu, 23 Jun 2011 13:35:04 -0400 |
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From: Dan Rosenberg <drosenberg@vsecurity.com>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. If you see a problem with using this for longterm, please comment. -------------------
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 <drosenberg@vsecurity.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- net/irda/af_irda.c | 16 +++++++++------- 1 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/net/irda/af_irda.c b/net/irda/af_irda.c index 6fae047..e63c226 100644 --- a/net/irda/af_irda.c +++ b/net/irda/af_irda.c @@ -2278,6 +2278,14 @@ 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); @@ -2287,15 +2295,9 @@ 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) { -- 1.7.4.4
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