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| author | Dan Carpenter <dan.carpenter@oracle.com> | 2017-09-30 14:27:41 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-10-04 10:30:53 +0200 |
| commit | bd14798650cd2a2befd7d96bbc466c2317a582db (patch) | |
| tree | 808271cac5e16c798a3705f34d5787dd807691b2 /drivers/vme | |
| parent | ebc4768ac4971eab4b570e733e47ac9dfd0e4175 (diff) | |
| download | lwn-bd14798650cd2a2befd7d96bbc466c2317a582db.tar.gz lwn-bd14798650cd2a2befd7d96bbc466c2317a582db.zip | |
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>
Diffstat (limited to 'drivers/vme')
| -rw-r--r-- | drivers/vme/vme.c | 18 |
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: |