Re: smb cifs: Linux 6.7 pre rc-1 kernel dump in smb2_get_aead_req

Damian Tometzki
2023-11-06T07:37:00Z

On Sun, 05. Nov 12:15, Eric Biggers wrote:
> On Sun, Nov 05, 2023 at 08:40:03PM +0100, Damian Tometzki wrote:
> > On Sun, 05. Nov 11:36, Eric Biggers wrote:
> > > On Sun, Nov 05, 2023 at 11:05:30AM -0700, Steve French wrote:
> > > > maybe related to this recent crypto patch?
> > > >
> > > > https://git.samba.org/?p=sfrench/cifs-2.6.git;a=commit;h=783fa2c94f4150fe1b7f7d88b3baf6d98f82b41b
> > > >
> > > > On Sun, Nov 5, 2023, 10:32 Damian Tometzki <damian@riscv-rocks.de> wrote:
> > > > > [ 83.530503] CPU: 7 PID: 4584 Comm: mount.cifs Tainted: G W
> > > > > 6.6.0 #61
> > > > > [ 83.530508] Hardware name: LENOVO 20XWCTO1WW/20XWCTO1WW, BIOS N32ET86W
> > > > > (1.62 ) 07/12/2023
> > >
> > > The above suggests that this warning occurred on 6.6, not on 6.7 pre rc1.
> > >
> > > - Eric
> > Hello,
> >
> > is little bit missleading but it is 6.6 from linus mainline git with all
> > the pull request.
> >
> > Damian
> >
>
> Okay, next time please mention the actual commit ID. Anyway, the warning is
> 'WARN_ON_ONCE(user_backed_iter(&rqst[i].rq_iter))', so maybe take a look at
> changes from
>
> commit f1b4cb650b9a0eeba206d8f069fcdc532bfbcd74
> Author: David Howells <dhowells@redhat.com>
> Date: Mon Sep 25 13:03:03 2023 +0100
>
> iov_iter: Derive user-backedness from the iterator type
>
Hello Eric,

the revert of f1b4cb650b9a0eeba206d8f069fcdc532bfbcd74 solved the issue of the kernel dump.

diff --git a/include/linux/uio.h b/include/linux/uio.h
index b6214cbf2a43..02a8e5e6c458 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -43,6 +43,7 @@ struct iov_iter {
bool copy_mc;
bool nofault;
bool data_source;
+ bool user_backed;
size_t iov_offset;
/*
* Hack alert: overlay ubuf_iovec with iovec + count, so
@@ -139,7 +140,7 @@ static inline unsigned char iov_iter_rw(const struct iov_iter *i)

static inline bool user_backed_iter(const struct iov_iter *i)
{
- return iter_is_ubuf(i) || iter_is_iovec(i);
+ return i->user_backed;
}

/*
@@ -358,6 +359,7 @@ static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
*i = (struct iov_iter) {
.iter_type = ITER_UBUF,
.copy_mc = false,
+ .user_backed = true,
.data_source = direction,
.ubuf = buf,
.count = count,
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index de7d11cf4c63..a077c15727b2 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -168,6 +168,7 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction,
.iter_type = ITER_IOVEC,
.copy_mc = false,
.nofault = false,
+ .user_backed = true,
.data_source = direction,
.__iov = iov,
.nr_segs = nr_segs,

> and the pull request that contained it:
>
> commit df9c65b5fc7ef1caabdb7a01a2415cbb8a00908d
> Merge: 3b3f874cc1d07 b5f0e20f444cd
> Author: Linus Torvalds <torvalds@linux-foundation.org>
> Date: Mon Oct 30 09:24:21 2023 -1000
>
> Merge tag 'vfs-6.7.iov_iter' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
>
> Pull iov_iter updates from Christian Brauner:
> "This contain's David's iov_iter cleanup work to convert the iov_iter
> iteration macros to inline functions: