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authorDan Carpenter <dan.carpenter@oracle.com>2017-09-30 14:27:41 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-10-04 10:30:53 +0200
commitbd14798650cd2a2befd7d96bbc466c2317a582db (patch)
tree808271cac5e16c798a3705f34d5787dd807691b2
parentebc4768ac4971eab4b570e733e47ac9dfd0e4175 (diff)
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vme: Fix integer overflow checking in vme_check_window()
The controversial part of this patch is that I've changed it so we now prevent integer overflows for VME_USER types and before we didn't. I view it as kernel-hardening. I looked at a couple places that used VME_USER types and they seemed pretty suspicious so I'm pretty sure preventing overflows here is a good idea. The most common problem which this function is for cases like VME_A16 where we don't put an upper bound on "size" so you could have "size" set to U64_MAX and a valid vme_base would overflow the "vme_base + size" into the valid range as well. In the VME_A64 case, the integer overflow checking doesn't work because "U64_MAX + 1" has an integer overflow and it's just a complicated way of saying zero. That VME_A64 case is sort of interesting as well because there is a VME_A64_MAX define which is set to "U64_MAX + 1". The compiler will never let anyone use it since it can't be stored in a u64 variable... With my patch it's now limited to just U64_MAX. Anyway, I put one integer overflow check at the start of the function and deleted all existing checks. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Dmitry Kalinkin <dmitry.kalinkin@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/vme/vme.c18
1 files changed, 8 insertions, 10 deletions
diff --git a/drivers/vme/vme.c b/drivers/vme/vme.c
index 6a3ead42aba8..5b4c898d7509 100644
--- a/drivers/vme/vme.c
+++ b/drivers/vme/vme.c
@@ -208,29 +208,27 @@ int vme_check_window(u32 aspace, unsigned long long vme_base,
{
int retval = 0;
+ if (vme_base + size < size)
+ return -EINVAL;
+
switch (aspace) {
case VME_A16:
- if (((vme_base + size) > VME_A16_MAX) ||
- (vme_base > VME_A16_MAX))
+ if (vme_base + size > VME_A16_MAX)
retval = -EFAULT;
break;
case VME_A24:
- if (((vme_base + size) > VME_A24_MAX) ||
- (vme_base > VME_A24_MAX))
+ if (vme_base + size > VME_A24_MAX)
retval = -EFAULT;
break;
case VME_A32:
- if (((vme_base + size) > VME_A32_MAX) ||
- (vme_base > VME_A32_MAX))
+ if (vme_base + size > VME_A32_MAX)
retval = -EFAULT;
break;
case VME_A64:
- if ((size != 0) && (vme_base > U64_MAX + 1 - size))
- retval = -EFAULT;
+ /* The VME_A64_MAX limit is actually U64_MAX + 1 */
break;
case VME_CRCSR:
- if (((vme_base + size) > VME_CRCSR_MAX) ||
- (vme_base > VME_CRCSR_MAX))
+ if (vme_base + size > VME_CRCSR_MAX)
retval = -EFAULT;
break;
case VME_USER1: