(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 Call Trace: dump_stack panic ? _raw_spin_unlock_irqrestore ? start_secondary __stack_chk_fail start_secondary secondary_startup (I wrote the above messages manually from a picture so expect typos) Then also on my x86 laptop I downgraded the compiler to GCC 8.1.0 (from crosstool), rebuilt the exactly same kernel version and the kernel booted without issues. I'm using 5.7.0-rc4-wt-ath+ which is basically v5.7-rc4 plus latest wireless patches, and I doubt the wireless patches are making any difference this early in the boot. All compilers I use are prebuilt binaries from kernel.org crosstool repo[1] with addition of ccache v3.4.1 to speed up my builds. Any ideas? How should I debug this further? [1] https://mirrors.edge.kernel.org/pub/tools/crosstool/ -- https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
