linux-hardening - Re: [PATCH v2] scsi: fcoe: use sysfs_match_string over fcoe_parse

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Date: Wed, 13 Dec 2023 08:07:33 +0100
From: Hannes Reinecke <hare@...e.de>
To: Justin Stitt <justinstitt@...gle.com>,
 "James E.J. Bottomley" <jejb@...ux.ibm.com>,
 "Martin K. Petersen" <martin.petersen@...cle.com>,
 Bart Van Assche <bvanassche@....org>
Cc: linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2] scsi: fcoe: use sysfs_match_string over
 fcoe_parse_mode

On 12/13/23 00:19, Justin Stitt wrote:
> Instead of copying @buf into a new buffer and carefully managing its
> newline/null-terminating status, we can just use sysfs_match_string()
> as it uses sysfs_streq() internally which handles newline/null-term:
> 
> |  /**
> |   * sysfs_streq - return true if strings are equal, modulo trailing newline
> |   * @s1: one string
> |   * @s2: another string
> |   *
> |   * This routine returns true iff two strings are equal, treating both
> |   * NUL and newline-then-NUL as equivalent string terminations.  It's
> |   * geared for use with sysfs input strings, which generally terminate
> |   * with newlines but are compared against values without newlines.
> |   */
> |  bool sysfs_streq(const char *s1, const char *s2)
> |  ...
> 
> Then entirely drop the now unused fcoe_parse_mode, being careful to
> change if condition from checking for FIP_CONN_TYPE_UNKNOWN to < 0 as
> sysfs_match_string can return -EINVAL. Also check explicitly if
> ctlr->mode is equal to FIP_CONN_TYPE_UNKNOWN -- this is probably
> preferred to "<=" as the behavior is more obvious while maintaining
> functionality.
> 
> To get the compiler not to complain, make fip_conn_type_names
> const char * const. Perhaps, this should also be done for
> fcf_state_names.
> 
> This also removes an instance of strncpy() which helps [1].
> 
> Link: https://github.com/KSPP/linux/issues/90 [1]
> Cc: linux-hardening@...r.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>
> ---
> Changes in v2:
> - update if-cond to check for unknown type (thanks Kees)
> - Link to v1: https://lore.kernel.org/r/20231211-strncpy-drivers-scsi-fcoe-fcoe_sysfs-c-v1-1-73b942238396@google.com
> ---
> Builds upon patch and feedback from [2]:
> 
> However, this is different enough to warrant its own patch and not be a
> continuation.
> 
> [2]: https://lore.kernel.org/all/9f38f4aa-c6b5-4786-a641-d02d8bd92f7f@acm.org/
> ---
>   drivers/scsi/fcoe/fcoe_sysfs.c | 26 ++++----------------------
>   1 file changed, 4 insertions(+), 22 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@...e.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@...e.de                              +49 911 74053 688
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