[PATCH v2 1/2] KVM: s390: Improve determination of sizes in kvm_s390_import_bp_data()

[SF Markus Elfring]

From: Markus Elfring <elfr...@users.sourceforge.net>
Date: Wed, 24 Aug 2016 19:45:23 +0200

* A multiplication for the size determination of a memory allocation
  indicated that an array data structure should be processed.
  Thus reuse the corresponding function "kmalloc_array".

  Suggested-by: Paolo Bonzini <pbonz...@redhat.com>

  This issue was detected also by using the Coccinelle software.

* Replace the specification of data structures by pointer dereferences
  to make the corresponding size determination a bit safer according to
  the Linux coding style convention.

* Delete the local variable "size" which became unnecessary with
  this refactoring.

Signed-off-by: Markus Elfring <elfr...@users.sourceforge.net>
---

v2: Rebased on source files from "Linux next-20160824".
    Advices were integrated from source code review.

 arch/s390/kvm/guestdbg.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/arch/s390/kvm/guestdbg.c b/arch/s390/kvm/guestdbg.c
index d1f8241..70b71ac 100644
--- a/arch/s390/kvm/guestdbg.c
+++ b/arch/s390/kvm/guestdbg.c
@@ -206,7 +206,7 @@ static int __import_wp_info(struct kvm_vcpu *vcpu,
 int kvm_s390_import_bp_data(struct kvm_vcpu *vcpu,
                            struct kvm_guest_debug *dbg)
 {
-       int ret = 0, nr_wp = 0, nr_bp = 0, i, size;
+       int ret = 0, nr_wp = 0, nr_bp = 0, i;
        struct kvm_hw_breakpoint *bp_data = NULL;
        struct kvm_hw_wp_info_arch *wp_info = NULL;
        struct kvm_hw_bp_info_arch *bp_info = NULL;
@@ -216,14 +216,17 @@ int kvm_s390_import_bp_data(struct kvm_vcpu *vcpu,
        else if (dbg->arch.nr_hw_bp > MAX_BP_COUNT)
                return -EINVAL;
 
-       size = dbg->arch.nr_hw_bp * sizeof(struct kvm_hw_breakpoint);
-       bp_data = kmalloc(size, GFP_KERNEL);
+       bp_data = kmalloc_array(dbg->arch.nr_hw_bp,
+                               sizeof(*bp_data),
+                               GFP_KERNEL);
        if (!bp_data) {
                ret = -ENOMEM;
                goto error;
        }
 
-       if (copy_from_user(bp_data, dbg->arch.hw_bp, size)) {
+       if (copy_from_user(bp_data,
+                          dbg->arch.hw_bp,
+                          sizeof(*bp_data) * dbg->arch.nr_hw_bp)) {
                ret = -EFAULT;
                goto error;
        }
@@ -241,17 +244,19 @@ int kvm_s390_import_bp_data(struct kvm_vcpu *vcpu,
                }
        }
 
-       size = nr_wp * sizeof(struct kvm_hw_wp_info_arch);
-       if (size > 0) {
-               wp_info = kmalloc(size, GFP_KERNEL);
+       if (nr_wp > 0) {
+               wp_info = kmalloc_array(nr_wp,
+                                       sizeof(*wp_info),
+                                       GFP_KERNEL);
                if (!wp_info) {
                        ret = -ENOMEM;
                        goto error;
                }
        }
-       size = nr_bp * sizeof(struct kvm_hw_bp_info_arch);
-       if (size > 0) {
-               bp_info = kmalloc(size, GFP_KERNEL);
+       if (nr_bp > 0) {
+               bp_info = kmalloc_array(nr_bp,
+                                       sizeof(*bp_info),
+                                       GFP_KERNEL);
                if (!bp_info) {
                        ret = -ENOMEM;
                        goto error;
-- 
2.9.3