On 2/3/23 11:53, Kees Cook wrote:
On Thu, Feb 02, 2023 at 07:24:50PM -0600, Gustavo A. R. Silva wrote:One-element arrays are deprecated, and we are replacing them with flexible array members instead. So, replace one-element arrays with flexible-array members in structures xfs_attr_leaf_name_local and xfs_attr_leaf_name_remote. The only binary differences reported after the changes are all like these: fs/xfs/libxfs/xfs_attr_leaf.o _@@ -435,7 +435,7 @@ 3b8: movzbl 0x2(%rbx),%eax 3bc: rol $0x8,%bp 3c0: movzwl %bp,%ebp - 3c3: lea 0x2(%rax,%rbp,1),%ebx + 3c3: lea 0x3(%rax,%rbp,1),%ebx 3c7: call 3cc <xfs_attr_leaf_entsize+0x8c> 3c8: R_X86_64_PLT32 __tsan_func_exit-0x4 3cc: or $0x3,%ebx _@@ -454,7 +454,7 @@ 3ea: movzbl 0x8(%rbx),%ebx 3ee: call 3f3 <xfs_attr_leaf_entsize+0xb3> 3ef: R_X86_64_PLT32 __tsan_func_exit-0x4 - 3f3: add $0xa,%ebx + 3f3: add $0xb,%ebx 3f6: or $0x3,%ebx 3f9: add $0x1,%ebx 3fc: mov %ebx,%eax similar changes in fs/xfs/scrub/attr.o and fs/xfs/xfs.o object files.I usually turn off the sanitizers for the A/B build comparisons to make
Oh yes! that's a good point. I'll see that they are turned off next time. :)
it easier to read the results. It looks like it _grew_ in size here, though?
Yep; I'm sorry I got it wrong. :/ I had it right in the beginning, then after reading the code once again just before sending out a version of this patch with only the flex-array transformations, I noticed the entsize functions and the "sizeof(struct-with-one-element-array) - 1" and I forgot about the padding, removed the "- 1" and got a bit confused with my build-tests. I'll send v2 with my original changes... the flex-array transformations, only. -- Gustavo
