libnm: suppress "-Warray-bounds" warning in nm_team_link_watcher_new_ethtool()

gcc-11.0.0-0.7.fc34 warns here:

    CC       libnm-core/libnm_core_la-nm-setting-team.lo
  libnm-core/nm-setting-team.c: In function ‘nm_team_link_watcher_new_ethtool’:
  libnm-core/nm-setting-team.c:127:33: error: array subscript ‘NMTeamLinkWatcher[0]’ is partly outside array bounds of ‘unsigned char[16]’ [-Werror=array-bounds]
    127 |     watcher->ref_count          = 1;
        |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
  libnm-core/nm-setting-team.c:125:15: note: referencing an object of size 16 allocated by ‘g_malloc’
    125 |     watcher = g_malloc(nm_offsetofend(NMTeamLinkWatcher, ethtool));
        |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  libnm-core/nm-setting-team.c:128:33: error: array subscript ‘NMTeamLinkWatcher[0]’ is partly outside array bounds of ‘unsigned char[16]’ [-Werror=array-bounds]
    128 |     watcher->type               = LINK_WATCHER_ETHTOOL;
        |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
  libnm-core/nm-setting-team.c:125:15: note: referencing an object of size 16 allocated by ‘g_malloc’
    125 |     watcher = g_malloc(nm_offsetofend(NMTeamLinkWatcher, ethtool));
        |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  libnm-core/nm-setting-team.c:129:33: error: array subscript ‘NMTeamLinkWatcher[0]’ is partly outside array bounds of ‘unsigned char[16]’ [-Werror=array-bounds]
    129 |     watcher->ethtool.delay_up   = delay_up;
        |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~
  libnm-core/nm-setting-team.c:125:15: note: referencing an object of size 16 allocated by ‘g_malloc’
    125 |     watcher = g_malloc(nm_offsetofend(NMTeamLinkWatcher, ethtool));
        |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  libnm-core/nm-setting-team.c:130:33: error: array subscript ‘NMTeamLinkWatcher[0]’ is partly outside array bounds of ‘unsigned char[16]’ [-Werror=array-bounds]
    130 |     watcher->ethtool.delay_down = delay_down;
        |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
  libnm-core/nm-setting-team.c:125:15: note: referencing an object of size 16 allocated by ‘g_malloc’
    125 |     watcher = g_malloc(nm_offsetofend(NMTeamLinkWatcher, ethtool));
        |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Maybe we should not use this trick and just malloc() a struct of the
intended size, however:

 - the code below does a similar thing, doing it differently for ethtool
   watcher is confusing.

 - the NMTeamLinkWatcher is a union which cannot alter its type. In no
   case is it correct to access the fields of the wrong union type. By
   allocating a smaller chunk, valgrind might catch such bugs.
   Also, NMTeamLinkWatcher's definition is private to the C source file,
   in no case must anybody assume that the rest of the buffer actually
   exists.

Hence, workaround the warning by suppressing it.

(cherry picked from commit e5699dbcb7)
(cherry picked from commit 221547bc21)
(cherry picked from commit 8f3cf4f3e8)
(cherry picked from commit 675c7df8c2)
This commit is contained in:
Thomas Haller 2020-12-11 11:43:38 +01:00
parent 3f13d4d50f
commit 6efbf3604f
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View file

@ -116,6 +116,8 @@ nm_team_link_watcher_new_ethtool (int delay_up,
return NULL;
}
NM_PRAGMA_WARNING_DISABLE("-Warray-bounds")
watcher = g_malloc (nm_offsetofend (NMTeamLinkWatcher, ethtool));
watcher->ref_count = 1;
@ -123,6 +125,8 @@ nm_team_link_watcher_new_ethtool (int delay_up,
watcher->ethtool.delay_up = delay_up;
watcher->ethtool.delay_down = delay_down;
NM_PRAGMA_WARNING_REENABLE
return watcher;
}