linux-kernel - [PATCH v2 0/3] scsi: qedf: sanitise uaccess

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Date:   Mon, 31 Jul 2023 10:40:31 +0200
From:   Oleksandr Natalenko <oleksandr@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-scsi@...r.kernel.org, Saurav Kashyap <skashyap@...vell.com>,
        Johannes Thumshirn <Johannes.Thumshirn@....com>,
        David Laight <David.Laight@...LAB.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>,
        Laurence Oberman <loberman@...hat.com>,
        Rob Evers <revers@...hat.com>
Subject: [PATCH v2 0/3] scsi: qedf: sanitise uaccess

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.

Changes since v1 [1]:

  * use scnprintf() for on-stack buffers too
  * adjust an on-stack buffer size in qedf_dbg_debug_cmd_read() to be a
    multiple of 8, and also size it properly
  * accumulate acks and reviews

[1] https://lore.kernel.org/lkml/20230728065819.139694-1-oleksandr@redhat.com/

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