linux-kernel - Re: [RFC PATCH 0/3] scsi: qedf: sanitise uaccess

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Date:   Mon, 24 Jul 2023 12:27:55 -0400
From:   Laurence Oberman <loberman@...hat.com>
To:     Oleksandr Natalenko <oleksandr@...hat.com>,
        linux-kernel@...r.kernel.org
Cc:     linux-scsi@...r.kernel.org, Saurav Kashyap <skashyap@...vell.com>,
        Javed Hasan <jhasan@...vell.com>,
        GR-QLogic-Storage-Upstream@...vell.com,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Jozef Bacik <jobacik@...hat.com>, Rob Evers <revers@...hat.com>
Subject: Re: [RFC PATCH 0/3] scsi: qedf: sanitise uaccess

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


[root@...storage5 host2]# ls
clear_stats  debug  driver_stats  fp_int  io_trace  offload_stats 
stop_io_on_error
[root@...storage5 host2]# cat stop_io_on_error
false
[root@...storage5 host2]# cat debug
debug mask = 0x2
[root@...storage5 host2]# cat fp_int

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