On Wed, Apr 08, 2026 at 02:21:19PM +0200, Thorsten Blum wrote: > On Wed, Apr 08, 2026 at 12:02:25PM +0300, Jarkko Sakkinen wrote: > > On Mon, Apr 06, 2026 at 07:58:10PM +0200, Thorsten Blum wrote: > > > Add the __counted_by() compiler attribute to the flexible array member > > > 'data' to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and > > > CONFIG_FORTIFY_SOURCE. > > > > > > Signed-off-by: Thorsten Blum <[email protected]> > > > --- > > > include/keys/user-type.h | 3 ++- > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > diff --git a/include/keys/user-type.h b/include/keys/user-type.h > > > index 386c31432789..2305991f4fcd 100644 > > > --- a/include/keys/user-type.h > > > +++ b/include/keys/user-type.h > > > @@ -27,7 +27,8 @@ > > > struct user_key_payload { > > > struct rcu_head rcu; /* RCU destructor */ > > > unsigned short datalen; /* length of this data */ > > > - char data[] __aligned(__alignof__(u64)); /* actual data */ > > > + char data[] /* actual data */ > > > + __aligned(__alignof__(u64)) __counted_by(datalen); > > > }; > > > > > > extern struct key_type key_type_user; > > > > You don't provide any evidence of any improvement. > > It's a proactive hardening change to help avoid future mistakes. > > The __counted_by() annotation makes the bounds visible to the compiler > and at runtime so that future ->data accesses can be checked against > ->datalen. > > The current code is correct regarding ->data accesses and doesn't > require any changes.
OK I'll buy that but send +1 version: ~/work/kernel.org/jarkko/linux-tpmdd next ❯ git am -3 20260406_thorsten_blum_keys_dns_drop_unused_upayload_data_nul_terminator.mbx Applying: keys, dns: drop unused upayload->data NUL terminator error: sha1 information is lacking or useless (net/dns_resolver/dns_key.c). error: could not build fake ancestor Patch failed at 0001 keys, dns: drop unused upayload->data NUL terminator hint: Use 'git am --show-current-patch=diff' to see the failed patch When you have resolved this problem, run "git am --continue". If you prefer to skip this patch, run "git am --skip" instead. To restore the original branch and stop patching, run "git am --abort". BR, Jarkko
