From 15bfacdb85394b6ea8b3debb23a681596e20f3aa Mon Sep 17 00:00:00 2001
From: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Date: Mon, 21 Oct 2024 13:37:53 +0100
Subject: [PATCH] vfio/qat: fix overflow check in qat_vf_resume_write()
commit 9283b7392570421c22a6c8058614f5b76a46b81c upstream.
The unsigned variable `size_t len` is cast to the signed type `loff_t`
when passed to the function check_add_overflow(). This function considers
the type of the destination, which is of type loff_t (signed),
potentially leading to an overflow. This issue is similar to the one
described in the link below.
Remove the cast.
Note that even if check_add_overflow() is bypassed, by setting `len` to
a value that is greater than LONG_MAX (which is considered as a negative
value after the cast), the function copy_from_user(), invoked a few lines
later, will not perform any copy and return `len` as (len > INT_MAX)
causing qat_vf_resume_write() to fail with -EFAULT.
Fixes: bb208810b1ab ("vfio/qat: Add vfio_pci driver for Intel QAT SR-IOV VF devices")
CC: stable@vger.kernel.org # 6.10+
Link: https://lore.kernel.org/all/138bd2e2-ede8-4bcc-aa7b-f3d9de167a37@moroto.mountain
Reported-by: Zijie Zhao <zzjas98@gmail.com>
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Reviewed-by: Xin Zeng <xin.zeng@intel.com>
Link: https://lore.kernel.org/r/20241021123843.42979-1-giovanni.cabiddu@intel.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/vfio/pci/qat/main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/vfio/pci/qat/main.c b/drivers/vfio/pci/qat/main.c
index be3644ced17be..c78cb6de93906 100644
--- a/drivers/vfio/pci/qat/main.c
+++ b/drivers/vfio/pci/qat/main.c
@@ -304,7 +304,7 @@ static ssize_t qat_vf_resume_write(struct file *filp, const char __user *buf,
offs = &filp->f_pos;
if (*offs < 0 ||
- check_add_overflow((loff_t)len, *offs, &end))
+ check_add_overflow(len, *offs, &end))
return -EOVERFLOW;
if (end > mig_dev->state_size)
--
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