On Sat, Mar 10, 2018 at 4:11 AM, Randy Dunlap <rdun...@infradead.org> wrote: > On 03/09/2018 04:07 PM, Andrew Morton wrote: >> On Fri, 9 Mar 2018 12:05:36 -0800 Kees Cook <keesc...@chromium.org> wrote: >> >>> When max() is used in stack array size calculations from literal values >>> (e.g. "char foo[max(sizeof(struct1), sizeof(struct2))]", the compiler >>> thinks this is a dynamic calculation due to the single-eval logic, which >>> is not needed in the literal case. This change removes several accidental >>> stack VLAs from an x86 allmodconfig build: >>> >>> $ diff -u before.txt after.txt | grep ^- >>> -drivers/input/touchscreen/cyttsp4_core.c:871:2: warning: ISO C90 forbids >>> variable length array ‘ids’ [-Wvla] >>> -fs/btrfs/tree-checker.c:344:4: warning: ISO C90 forbids variable length >>> array ‘namebuf’ [-Wvla] >>> -lib/vsprintf.c:747:2: warning: ISO C90 forbids variable length array ‘sym’ >>> [-Wvla] >>> -net/ipv4/proc.c:403:2: warning: ISO C90 forbids variable length array >>> ‘buff’ [-Wvla] >>> -net/ipv6/proc.c:198:2: warning: ISO C90 forbids variable length array >>> ‘buff’ [-Wvla] >>> -net/ipv6/proc.c:218:2: warning: ISO C90 forbids variable length array >>> ‘buff64’ [-Wvla] >>> >>> Based on an earlier patch from Josh Poimboeuf. >> >> v1, v2 and v3 of this patch all fail with gcc-4.4.4: >> >> ./include/linux/jiffies.h: In function 'jiffies_delta_to_clock_t': >> ./include/linux/jiffies.h:444: error: first argument to >> '__builtin_choose_expr' not a constant > > > I'm seeing that problem with >> gcc --version > gcc (SUSE Linux) 4.8.5
Same here, 4.8.5 fails. gcc 5.4.1 seems to work. I compiled a minimal 5.1.0 and it seems to work as well. Cheers, Miguel
