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

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Date: Tue, 12 Dec 2023 18:33:17 -0800
From: Kees Cook <keescook@...omium.org>
To: Justin Stitt <justinstitt@...gle.com>
Cc: Hannes Reinecke <hare@...e.de>,
	"James E.J. Bottomley" <jejb@...ux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	Bart Van Assche <bvanassche@....org>, 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 Tue, Dec 12, 2023 at 11:19:06PM +0000, 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>

Looks great; thanks!

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook