In the Linux kernel, the following vulnerability has been resolved: net: use a bounce buffer for copying skb->mark syzbot found arm64 builds would crash in sock_recv_mark() when CONFIG_HARDENED_USERCOPY=y x86 and powerpc are not detecting the issue because they define user_access_begin. This will be handled in a different patch, because a check_object_size() is missing. Only data from skb->cb[] can be copied directly to/from user space, as explained in commit 79a8a642bf05 ("net: Whitelist the skbuff_head_cache "cb" field") syzbot report was: usercopy: Kernel memory exposure attempt detected from SLUB object 'skbuff_head_cache' (offset 168, size 4)! ------------[ cut here ]------------ kernel BUG at mm/usercopy.c:102 ! Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP Modul