qedf driver, debugfs part of it specifically, touches __user pointers
directly for printing out info to userspace via sprintf(), which may
cause crash like this:

BUG: unable to handle kernel paging request at 00007ffd1d6b43a0
IP: [<ffffffffaa7a882a>] string.isra.7+0x6a/0xf0
Oops: 0003 [#1] SMP
Call Trace:
 [<ffffffffaa7a9f31>] vsnprintf+0x201/0x6a0
 [<ffffffffaa7aa556>] sprintf+0x56/0x80
 [<ffffffffc04227ed>] qedf_dbg_stop_io_on_error_cmd_read+0x6d/0x90 [qedf]
 [<ffffffffaa65bb2f>] vfs_read+0x9f/0x170
 [<ffffffffaa65cb82>] SyS_pread64+0x92/0xc0

Avoid this by preparing the info in a kernel buffer first, either
allocated on stack for small printouts, or via vmalloc() for big ones,
and then copying it to the userspace properly.

I'm not sure how big the vmalloc()'ed buffer should be, and also whether
vmalloc()'ing it directly in the _read() function is a good idea, hence
RFC prefix.

The qedf_dbg_stop_io_on_error_cmd_read()-related patch is actually tested,
the rest is compile-tested only.

Oleksandr Natalenko (3):
  scsi: qedf: do not touch __user pointer in
    qedf_dbg_stop_io_on_error_cmd_read() directly
  scsi: qedf: do not touch __user pointer in qedf_dbg_debug_cmd_read()
    directly
  scsi: qedf: do not touch __user pointer in qedf_dbg_fp_int_cmd_read()
    directly

 drivers/scsi/qedf/qedf_dbg.h     |  2 ++
 drivers/scsi/qedf/qedf_debugfs.c | 35 +++++++++++++++++++-------------
 2 files changed, 23 insertions(+), 14 deletions(-)

--
2.41.0

On Mon, 2023-07-24 at 14:02 +0200, Oleksandr Natalenko wrote:
> qedf driver, debugfs part of it specifically, touches __user pointers
> directly for printing out info to userspace via sprintf(), which may
> cause crash like this:
> 
> BUG: unable to handle kernel paging request at 00007ffd1d6b43a0
> IP: [<ffffffffaa7a882a>] string.isra.7+0x6a/0xf0
> Oops: 0003 [#1] SMP
> Call Trace:
>  [<ffffffffaa7a9f31>] vsnprintf+0x201/0x6a0
>  [<ffffffffaa7aa556>] sprintf+0x56/0x80
>  [<ffffffffc04227ed>] qedf_dbg_stop_io_on_error_cmd_read+0x6d/0x90
> [qedf]
>  [<ffffffffaa65bb2f>] vfs_read+0x9f/0x170
>  [<ffffffffaa65cb82>] SyS_pread64+0x92/0xc0
> 
> Avoid this by preparing the info in a kernel buffer first, either
> allocated on stack for small printouts, or via vmalloc() for big
> ones,
> and then copying it to the userspace properly.
> 
> I'm not sure how big the vmalloc()'ed buffer should be, and also
> whether
> vmalloc()'ing it directly in the _read() function is a good idea,
> hence
> RFC prefix.
> 
> The qedf_dbg_stop_io_on_error_cmd_read()-related patch is actually
> tested,
> the rest is compile-tested only.
> 
> Oleksandr Natalenko (3):
>   scsi: qedf: do not touch __user pointer in
>     qedf_dbg_stop_io_on_error_cmd_read() directly
>   scsi: qedf: do not touch __user pointer in
> qedf_dbg_debug_cmd_read()
>     directly
>   scsi: qedf: do not touch __user pointer in
> qedf_dbg_fp_int_cmd_read()
>     directly
> 
>  drivers/scsi/qedf/qedf_dbg.h     |  2 ++
>  drivers/scsi/qedf/qedf_debugfs.c | 35 +++++++++++++++++++-----------
> --
>  2 files changed, 23 insertions(+), 14 deletions(-)
> 
> --
> 2.41.0
> 

I will test the series, the one patch was already tested.
This was reproduced in our LAB
Will report back after testing

Regards
Laurence

On Mon, 2023-07-24 at 09:03 -0400, Laurence Oberman wrote:
> On Mon, 2023-07-24 at 14:02 +0200, Oleksandr Natalenko wrote:
> > qedf driver, debugfs part of it specifically, touches __user
> > pointers
> > directly for printing out info to userspace via sprintf(), which
> > may
> > cause crash like this:
> > 
> > BUG: unable to handle kernel paging request at 00007ffd1d6b43a0
> > IP: [<ffffffffaa7a882a>] string.isra.7+0x6a/0xf0
> > Oops: 0003 [#1] SMP
> > Call Trace:
> >  [<ffffffffaa7a9f31>] vsnprintf+0x201/0x6a0
> >  [<ffffffffaa7aa556>] sprintf+0x56/0x80
> >  [<ffffffffc04227ed>] qedf_dbg_stop_io_on_error_cmd_read+0x6d/0x90
> > [qedf]
> >  [<ffffffffaa65bb2f>] vfs_read+0x9f/0x170
> >  [<ffffffffaa65cb82>] SyS_pread64+0x92/0xc0
> > 
> > Avoid this by preparing the info in a kernel buffer first, either
> > allocated on stack for small printouts, or via vmalloc() for big
> > ones,
> > and then copying it to the userspace properly.
> > 
> > I'm not sure how big the vmalloc()'ed buffer should be, and also
> > whether
> > vmalloc()'ing it directly in the _read() function is a good idea,
> > hence
> > RFC prefix.
> > 
> > The qedf_dbg_stop_io_on_error_cmd_read()-related patch is actually
> > tested,
> > the rest is compile-tested only.
> > 
> > Oleksandr Natalenko (3):
> >   scsi: qedf: do not touch __user pointer in
> >     qedf_dbg_stop_io_on_error_cmd_read() directly
> >   scsi: qedf: do not touch __user pointer in
> > qedf_dbg_debug_cmd_read()
> >     directly
> >   scsi: qedf: do not touch __user pointer in
> > qedf_dbg_fp_int_cmd_read()
> >     directly
> > 
> >  drivers/scsi/qedf/qedf_dbg.h     |  2 ++
> >  drivers/scsi/qedf/qedf_debugfs.c | 35 +++++++++++++++++++---------
> > --
> > --
> >  2 files changed, 23 insertions(+), 14 deletions(-)
> > 
> > --
> > 2.41.0
> > 
> 
> I will test the series, the one patch was already tested.
> This was reproduced in our LAB
> Will report back after testing
> 
> Regards
> Laurence

For the series:  Against 6.5.0-rc3
Makes sense to me and tested.

Reviewed-by: Laurence Oberman <loberman@redhat.com>
Tested-by: Laurence Oberman <loberman@redhat.com>


[root@segstorage5 host2]# ls
clear_stats  debug  driver_stats  fp_int  io_trace  offload_stats 
stop_io_on_error
[root@segstorage5 host2]# cat stop_io_on_error
false
[root@segstorage5 host2]# cat debug
debug mask = 0x2
[root@segstorage5 host2]# cat fp_int

Fastpath I/O completions

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