Re: [PATCH ipsec-next v3] net: ipv6: fix field-spanning memcpy warning in AH output

[Steffen Klassert]

On Tue, Aug 12, 2025 at 03:51:25PM +0000, Charalampos Mitrodimas wrote:
> Fix field-spanning memcpy warnings in ah6_output() and
> ah6_output_done() where extension headers are copied to/from IPv6
> address fields, triggering fortify-string warnings about writes beyond
> the 16-byte address fields.
> 
>   memcpy: detected field-spanning write (size 40) of single field "&top_iph->saddr" at net/ipv6/ah6.c:439 (size 16)
>   WARNING: CPU: 0 PID: 8838 at net/ipv6/ah6.c:439 ah6_output+0xe7e/0x14e0 net/ipv6/ah6.c:439
> 
> The warnings are false positives as the extension headers are
> intentionally placed after the IPv6 header in memory. Fix by properly
> copying addresses and extension headers separately, and introduce
> helper functions to avoid code duplication.
> 
> Reported-by: syzbot+01b0667934cdceb4451c@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://syzkaller.appspot.com/bug?extid=01b0667934cdceb4451c
> Signed-off-by: Charalampos Mitrodimas <charmitro@xxxxxxxxxx>

Applied, thanks a lot!