On Wed, May 13, 2020 at 09:50:03AM +0300, Kalle Valo wrote: > (trimming CC, changing title) > > Kalle Valo <kvalo@xxxxxxxxxxxxxx> writes: > > > Kalle Valo <kvalo@xxxxxxxxxxxxxx> writes: > > > >> Arnd Bergmann <arnd@xxxxxxxx> writes: > >> > >>> gcc-10 correctly points out a bug with a zero-length array in > >>> struct ath10k_pci: > >>> > >>> drivers/net/wireless/ath/ath10k/ahb.c: In function 'ath10k_ahb_remove': > >>> drivers/net/wireless/ath/ath10k/ahb.c:30:9: error: array subscript 0 > >>> is outside the bounds of an interior zero-length array 'struct > >>> ath10k_ahb[0]' [-Werror=zero-length-bounds] > >>> 30 | return &((struct ath10k_pci *)ar->drv_priv)->ahb[0]; > >>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > >>> In file included from drivers/net/wireless/ath/ath10k/ahb.c:13: > >>> drivers/net/wireless/ath/ath10k/pci.h:185:20: note: while referencing 'ahb' > >>> 185 | struct ath10k_ahb ahb[0]; > >>> | ^~~ > >>> > >>> The last addition to the struct ignored the comments and added > >>> new members behind the array that must remain last. > >>> > >>> Change it to a flexible-array member and move it last again to > >>> make it work correctly, prevent the same thing from happening > >>> again (all compilers warn about flexible-array members in the > >>> middle of a struct) and get it to build without warnings. > >> > >> Very good find, thanks! This bug would cause all sort of strange memory > >> corruption issues. > > > > This motivated me to switch to using GCC 10.x and I noticed that you had > > already upgraded crosstool so it was a trivial thing to do, awesome :) > > > > https://mirrors.edge.kernel.org/pub/tools/crosstool/ > > And now I have a problem :) I first noticed that my x86 testbox is not > booting when I compile the kernel with GCC 10.1.0 from crosstool. I > didn't get any error messages so I just downgraded the compiler and the > kernel was booting fine again. Next I decided to try GCC 10.1 with my > x86 laptop and it also failed to boot, but this time I got kernel logs > and saw this: > > Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: start_secodary+0x178/0x180 > See https://lore.kernel.org/lkml/20200423161126.GD26021@xxxxxxx/
