[Qemu-commits] [qemu/qemu] 9d7a4c: coverity: Improve model for GLib memory allocation

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/qemu/qemu
  Commit: 9d7a4c6690ef9962a3b20034f65008f1ea15c1d6
      
https://github.com/qemu/qemu/commit/9d7a4c6690ef9962a3b20034f65008f1ea15c1d6
  Author: Markus Armbruster <address@hidden>
  Date:   2015-02-05 (Thu, 05 Feb 2015)

  Changed paths:
    M scripts/coverity-model.c

  Log Message:
  -----------
  coverity: Improve model for GLib memory allocation

In current versions of GLib, g_new() may expand into g_malloc_n().
When it does, Coverity can't see the memory allocation, because we
don't model g_malloc_n().  Similarly for g_new0(), g_renew(),
g_try_new(), g_try_new0(), g_try_renew().

Model g_malloc_n(), g_malloc0_n(), g_realloc_n().  Model
g_try_malloc_n(), g_try_malloc0_n(), g_try_realloc_n() by adding
indeterminate out of memory conditions on top.

To avoid undue duplication, replace the existing models for g_malloc()
& friends by trivial wrappers around g_malloc_n() & friends.

In a local scan, this flags four additional RESOURCE_LEAKs and one
NULL_RETURNS.

The NULL_RETURNS is a false positive: Coverity can now see that
g_try_malloc(l1_sz * sizeof(uint64_t)) in
qcow2_check_metadata_overlap() may return NULL, but is too stupid to
recognize that a loop executing l1_sz times won't be entered then.

Three out of the four RESOURCE_LEAKs appear genuine.  The false
positive is in ppce500_prep_device_tree(): the pointer dies, but a
pointer to a struct member escapes, and we get the pointer back for
freeing with container_of().  Too funky for Coverity.

Signed-off-by: Markus Armbruster <address@hidden>
Acked-by: Paolo Bonzini <address@hidden>


  Commit: e4b77daa5724a9dd41aaa44d2dea4b8e92351081
      
https://github.com/qemu/qemu/commit/e4b77daa5724a9dd41aaa44d2dea4b8e92351081
  Author: Markus Armbruster <address@hidden>
  Date:   2015-02-05 (Thu, 05 Feb 2015)

  Changed paths:
    M scripts/coverity-model.c

  Log Message:
  -----------
  coverity: Model GLib string allocation partially

Without a model, Coverity can't know that the result of g_strdup()
needs to be fed to g_free().

One way to get such a model is to scan GLib, build a derived model
file with cov-collect-models, and use that when scanning QEMU.
Unfortunately, the Coverity Scan service we use doesn't support that.

Thus, we're stuck with the other way: write a user model.  Doing that
for all of GLib is hardly practical.  I'm doing it for the "String
Utility Functions" we actually use that return dynamically allocated
strings.

In a local scan, this flags 20 additional RESOURCE_LEAKs.  The ones I
checked look genuine.

It also loses a NULL_RETURNS about ppce500_init() using
qemu_find_file() without error checking.  I don't understand why.

Signed-off-by: Markus Armbruster <address@hidden>
Acked-by: Paolo Bonzini <address@hidden>


  Commit: 7ad4c7200111d20eb97eed4f46b6026e3f0b0eef
      
https://github.com/qemu/qemu/commit/7ad4c7200111d20eb97eed4f46b6026e3f0b0eef
  Author: Markus Armbruster <address@hidden>
  Date:   2015-02-05 (Thu, 05 Feb 2015)

  Changed paths:
    M scripts/coverity-model.c

  Log Message:
  -----------
  coverity: Model g_free() isn't necessarily free()

Memory allocated with GLib needs to be freed with GLib.  Freeing it
with free() instead of g_free() is a common error.  Harmless when
g_free() is a trivial wrapper around free(), which is commonly the
case.  But model the difference anyway.

In a local scan, this flags four ALLOC_FREE_MISMATCH.  Requires
--enable ALLOC_FREE_MISMATCH, because the checker is still preview.

Signed-off-by: Markus Armbruster <address@hidden>
Acked-by: Paolo Bonzini <address@hidden>


  Commit: 8c413e7902ef0c19ced516f575db989ccc3785f8
      
https://github.com/qemu/qemu/commit/8c413e7902ef0c19ced516f575db989ccc3785f8
  Author: Markus Armbruster <address@hidden>
  Date:   2015-02-05 (Thu, 05 Feb 2015)

  Changed paths:
    M MAINTAINERS

  Log Message:
  -----------
  MAINTAINERS: Add myself as Coverity model maintainer

Suggested-by: Paolo Bonzini <address@hidden>
Signed-off-by: Markus Armbruster <address@hidden>


  Commit: 651621b780515f35711c5d7305310ab1d241c7e2
      
https://github.com/qemu/qemu/commit/651621b780515f35711c5d7305310ab1d241c7e2
  Author: Peter Maydell <address@hidden>
  Date:   2015-02-05 (Thu, 05 Feb 2015)

  Changed paths:
    M MAINTAINERS
    M scripts/coverity-model.c

  Log Message:
  -----------
  Merge remote-tracking branch 'remotes/armbru/tags/pull-cov-model-2015-02-05' 
into staging

coverity: Improve and extend model

# gpg: Signature made Thu 05 Feb 2015 16:20:49 GMT using RSA key ID EB918653
# gpg: Good signature from "Markus Armbruster <address@hidden>"
# gpg:                 aka "Markus Armbruster <address@hidden>"

* remotes/armbru/tags/pull-cov-model-2015-02-05:
  MAINTAINERS: Add myself as Coverity model maintainer
  coverity: Model g_free() isn't necessarily free()
  coverity: Model GLib string allocation partially
  coverity: Improve model for GLib memory allocation

Signed-off-by: Peter Maydell <address@hidden>


Compare: https://github.com/qemu/qemu/compare/cd07b19307bd...651621b78051