[pve-devel] [PATCH v2 qemu] fix #4726: avoid superfluous check in vma code

[pve-devel] [PATCH v2 qemu] fix #4726: avoid superfluous check in vma code

[Fiona Ebner]

The 'status' pointer is dereferenced regardless of the NULL check,
i.e. 'status->closed' is accessed after the branch with the check.
Since all callers pass in the address of a struct on the stack, the
pointer can never be NULL. Remove the superfluous check and add an
assert instead.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---

Changes in v2:
    * Clarify wording in commit message.

 ...VE-Backup-add-vma-backup-format-code.patch | 23 +++++++++----------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/debian/patches/pve/0027-PVE-Backup-add-vma-backup-format-code.patch b/debian/patches/pve/0027-PVE-Backup-add-vma-backup-format-code.patch
index ee40ab8..d6d7767 100644
--- a/debian/patches/pve/0027-PVE-Backup-add-vma-backup-format-code.patch
+++ b/debian/patches/pve/0027-PVE-Backup-add-vma-backup-format-code.patch
@@ -16,10 +16,10 @@ Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
  block/meson.build |   2 +
  meson.build       |   5 +
  vma-reader.c      | 870 ++++++++++++++++++++++++++++++++++++++++++++
- vma-writer.c      | 818 +++++++++++++++++++++++++++++++++++++++++
+ vma-writer.c      | 817 +++++++++++++++++++++++++++++++++++++++++
  vma.c             | 901 ++++++++++++++++++++++++++++++++++++++++++++++
  vma.h             | 150 ++++++++
- 6 files changed, 2746 insertions(+)
+ 6 files changed, 2745 insertions(+)
  create mode 100644 vma-reader.c
  create mode 100644 vma-writer.c
  create mode 100644 vma.c
@@ -939,10 +939,10 @@ index 0000000000..d0b6721812
 +
 diff --git a/vma-writer.c b/vma-writer.c
 new file mode 100644
-index 0000000000..126b296647
+index 0000000000..a466652a5d
 --- /dev/null
 +++ b/vma-writer.c
-@@ -0,0 +1,818 @@
+@@ -0,0 +1,817 @@
 +/*
 + * VMA: Virtual Machine Archive
 + *
@@ -1517,17 +1517,16 @@ index 0000000000..126b296647
 +    int i;
 +
 +    g_assert(vmaw != NULL);
++    g_assert(status != NULL);
 +
-+    if (status) {
-+        status->status = vmaw->status;
-+        g_strlcpy(status->errmsg, vmaw->errmsg, sizeof(status->errmsg));
-+        for (i = 0; i <= 255; i++) {
-+            status->stream_info[i] = vmaw->stream_info[i];
-+        }
-+
-+        uuid_unparse_lower(vmaw->uuid, status->uuid_str);
++    status->status = vmaw->status;
++    g_strlcpy(status->errmsg, vmaw->errmsg, sizeof(status->errmsg));
++    for (i = 0; i <= 255; i++) {
++        status->stream_info[i] = vmaw->stream_info[i];
 +    }
 +
++    uuid_unparse_lower(vmaw->uuid, status->uuid_str);
++
 +    status->closed = vmaw->closed;
 +
 +    return vmaw->status;
-- 
2.39.2



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[pve-devel] applied: [PATCH v2 qemu] fix #4726: avoid superfluous check in vma code

[Fiona Ebner]

Am 14.06.24 um 13:00 schrieb Fiona Ebner:
> The 'status' pointer is dereferenced regardless of the NULL check,
> i.e. 'status->closed' is accessed after the branch with the check.
> Since all callers pass in the address of a struct on the stack, the
> pointer can never be NULL. Remove the superfluous check and add an
> assert instead.
> 
> Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>

applied with Fabian's R-b given for v1, because it's the very same
change, but v2 has a slightly improved commit message.


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