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    SubjectRe: [PATCH] [v2] staging: rtl8723bs: avoid bogus gcc warning
    On Tue, Apr 27, 2021 at 01:59:32PM +0200, Arnd Bergmann wrote:
    > On Tue, Apr 27, 2021 at 11:33 AM Greg Kroah-Hartman
    > <gregkh@linuxfoundation.org> wrote:
    > >
    > > On Thu, Apr 22, 2021 at 05:26:19PM +0200, Arnd Bergmann wrote:
    > > > From: Arnd Bergmann <arnd@arndb.de>
    > > >
    > > > gcc gets confused by some of the type casts and produces an
    > > > apparently senseless warning about an out-of-bound memcpy to
    > > > an unrelated array in the same structure:
    > > >
    > > > drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c: In function 'rtw_cfg80211_ap_set_encryption':
    > > > cc1: error: writing 8 bytes into a region of size 0 [-Werror=stringop-overflow=]
    > > > In file included from drivers/staging/rtl8723bs/include/drv_types.h:32,
    > > > from drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c:10:
    > > > drivers/staging/rtl8723bs/include/rtw_security.h:98:15: note: at offset [184, 4264] into destination object 'dot11AuthAlgrthm' of size 4
    > > > 98 | u32 dot11AuthAlgrthm; /* 802.11 auth, could be open, shared, 8021x and authswitch */
    > > > | ^~~~~~~~~~~~~~~~
    > > > cc1: error: writing 8 bytes into a region of size 0 [-Werror=stringop-overflow=]
    > > > drivers/staging/rtl8723bs/include/rtw_security.h:98:15: note: at offset [264, 4344] into destination object 'dot11AuthAlgrthm' of size 4
    > > >
    > > > This is a known gcc bug, and the patch here is only a workaround,
    > > > but the approach of using a temporary variable to hold a pointer
    > > > to the key also improves readability in addition to avoiding the
    > > > warning, so overall this should still help.
    > >
    > > What version of gcc causes this? Should this go into 5.13-final and be
    > > backported? Or is this only showing up on "unreleased" versions of gcc
    > > and it is safe to wait until 5.14?
    >
    > As I understand, this is related to
    > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99673
    >
    > gcc-11.1.0 has now been released and it produces this warning.

    What's the odds we can get gcc to fix their bug, as it's not a kernel
    issue? :)

    thanks,

    greg k-h

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