diff mbox series

[v4,4/8] qemu-img: assert block_job_get() does not return NULL in img_commit()

Message ID 1539981546-10596-5-git-send-email-Liam.Merwick@oracle.com
State New
Headers show
Series off-by-one and NULL pointer accesses detected by static analysis | expand

Commit Message

Liam Merwick Oct. 19, 2018, 8:39 p.m. UTC 
Although the function block_job_get() can return NULL, it would be a
serious bug if it did so (because the job yields before executing anything
(if it started successfully); but otherwise, commit_active_start() would
have returned an error).  However, as a precaution, before dereferencing
the 'job' pointer in img_commit() assert it is not NULL.

Signed-off-by: Liam Merwick <Liam.Merwick@oracle.com>
---
 qemu-img.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Max Reitz Nov. 4, 2018, 11:59 p.m. UTC | #1 
On 19.10.18 22:39, Liam Merwick wrote:
> Although the function block_job_get() can return NULL, it would be a
> serious bug if it did so (because the job yields before executing anything
> (if it started successfully); but otherwise, commit_active_start() would
> have returned an error).  However, as a precaution, before dereferencing
> the 'job' pointer in img_commit() assert it is not NULL.

(In the meantime, Markus has argued to me in some other case that
asserting that something isn't NULL is just as good as just
dereferencing it.  Oh well, I still don't mind either way.)

> Signed-off-by: Liam Merwick <Liam.Merwick@oracle.com>
> ---
>  qemu-img.c | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Max Reitz <mreitz@redhat.com>
diff mbox series

Patch

diff --git a/qemu-img.c b/qemu-img.c
index b12f4cd19b0a..457aa152296b 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1029,6 +1029,7 @@  static int img_commit(int argc, char **argv)
     }
 
     job = block_job_get("commit");
+    assert(job);
     run_block_job(job, &local_err);
     if (local_err) {
         goto unref_backing;