Messages in this thread | | | Date | Wed, 10 Jan 2018 13:16:33 +0100 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH 4.4] net/mac80211/debugfs.c: prevent build failure with CONFIG_UBSAN=y |
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On Tue, Jan 09, 2018 at 12:53:27PM +0100, Daniel Wagner wrote: > From: Andrey Ryabinin <aryabinin@virtuozzo.com> > > commit 68920c973254c5b71a684645c5f6f82d6732c5d6 upstream. > > With upcoming CONFIG_UBSAN the following BUILD_BUG_ON in > net/mac80211/debugfs.c starts to trigger: > > BUILD_BUG_ON(hw_flag_names[NUM_IEEE80211_HW_FLAGS] != (void *)0x1); > > It seems, that compiler instrumentation causes some code > deoptimizations. Because of that GCC is not being able to resolve > condition in BUILD_BUG_ON() at compile time. > > We could make size of hw_flag_names array unspecified and replace the > condition in BUILD_BUG_ON() with following: > > ARRAY_SIZE(hw_flag_names) != NUM_IEEE80211_HW_FLAGS > > That will have the same effect as before (adding new flag without > updating array will trigger build failure) except it doesn't fail with > CONFIG_UBSAN. As a bonus this patch slightly decreases size of > hw_flag_names array. > > Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> > Cc: Johannes Berg <johannes@sipsolutions.net> > Cc: "David S. Miller" <davem@davemloft.net> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> > [Daniel: backport to 4.4.] > Signed-off-by: Daniel Wagner <daniel.wagner@siemens.com> > --- > > Hi, > > The only stable tree which is missing this fix is 4.4. 4.1 doesn't > have 30686bf7f5b3 ("mac80211: convert HW flags to unsigned long > bitmap") which makes gcc unhappy with allmodconfig. 4.9 contains the > fix.
Now queued up, thanks for the backport.
greg k-h
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