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@xxxxxxxxxxxxxxx # 6.10+
Link: https://lore.kernel.org/all/138bd2e2-ede8-4bcc-aa7b-f3d9de167a37@moroto.mountain
Reported-by: Zijie Zhao <zzjas98@xxxxxxxxx>
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@xxxxxxxxx>
Reviewed-by: Xin Zeng <xin.zeng@xxxxxxxxx>
---
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 e36740a282e7..1e3563fe7cab 100644
--- a/drivers/vfio/pci/qat/main.c
+++ b/drivers/vfio/pci/qat/main.c
@@ -305,7 +305,7 @@ 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)
--
2.47.0
