diff mbox series

[09/10] scsi: aic94xx: Remove snprintf() from sysfs call-backs and replace with sysfs_emit()

Message ID 20240208084512.3803250-10-lee@kernel.org
State New
Headers show
Series scsi: Replace {v}snprintf() variants with safer alternatives | expand

Commit Message

Lee Jones Feb. 8, 2024, 8:44 a.m. UTC 
Since snprintf() has the documented, but still rather strange trait of
returning the length of the data that *would have been* written to the
array if space were available, rather than the arguably more useful
length of data *actually* written, it is usually considered wise to use
something else instead in order to avoid confusion.

In the case of sysfs call-backs, new wrappers exist that do just that.

Link: https://lwn.net/Articles/69419/
Link: https://github.com/KSPP/linux/issues/105
Signed-off-by: Lee Jones <lee@kernel.org>
---
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Luben Tuikov <luben_tuikov@adaptec.com>
Cc: linux-scsi@vger.kernel.org
---
 drivers/scsi/aic94xx/aic94xx_init.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

Comments

Kees Cook Feb. 10, 2024, 7:13 a.m. UTC | #1 
On Thu, Feb 08, 2024 at 08:44:21AM +0000, Lee Jones wrote:
> Since snprintf() has the documented, but still rather strange trait of
> returning the length of the data that *would have been* written to the
> array if space were available, rather than the arguably more useful
> length of data *actually* written, it is usually considered wise to use
> something else instead in order to avoid confusion.
> 
> In the case of sysfs call-backs, new wrappers exist that do just that.

Actually, a treewide replacement for snprintf(dst, PAGE_SIZE, ... to
sysfs_emit might be workable too. Here's the .cocci file I made quickly:

@replace@
expression DST;
@@

- snprintf(DST, PAGE_SIZE,
+ sysfs_emit(DST,
  ...)

This produced almost 1000 changes:
 118 files changed, 964 insertions(+), 958 deletions(-)

Some need some manual examination, like:

arch/powerpc/platforms/ps3/system-bus.c:modalias_show() does:

        return (len >= PAGE_SIZE) ? (PAGE_SIZE - 1) : len;

which isn't needed any more.

Regardless,

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

-Kees
diff mbox series

Patch

diff --git a/drivers/scsi/aic94xx/aic94xx_init.c b/drivers/scsi/aic94xx/aic94xx_init.c
index 8a3340d8d7ad4..c976e4b77c71e 100644
--- a/drivers/scsi/aic94xx/aic94xx_init.c
+++ b/drivers/scsi/aic94xx/aic94xx_init.c
@@ -264,8 +264,7 @@  static ssize_t asd_show_dev_rev(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	struct asd_ha_struct *asd_ha = dev_to_asd_ha(dev);
-	return snprintf(buf, PAGE_SIZE, "%s\n",
-			asd_dev_rev[asd_ha->revision_id]);
+	return sysfs_emit(buf, "%s\n", asd_dev_rev[asd_ha->revision_id]);
 }
 static DEVICE_ATTR(aic_revision, S_IRUGO, asd_show_dev_rev, NULL);
 
@@ -273,7 +272,7 @@  static ssize_t asd_show_dev_bios_build(struct device *dev,
 				       struct device_attribute *attr,char *buf)
 {
 	struct asd_ha_struct *asd_ha = dev_to_asd_ha(dev);
-	return snprintf(buf, PAGE_SIZE, "%d\n", asd_ha->hw_prof.bios.bld);
+	return sysfs_emit(buf, "%d\n", asd_ha->hw_prof.bios.bld);
 }
 static DEVICE_ATTR(bios_build, S_IRUGO, asd_show_dev_bios_build, NULL);
 
@@ -281,7 +280,7 @@  static ssize_t asd_show_dev_pcba_sn(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
 	struct asd_ha_struct *asd_ha = dev_to_asd_ha(dev);
-	return snprintf(buf, PAGE_SIZE, "%s\n", asd_ha->hw_prof.pcba_sn);
+	return sysfs_emit(buf, "%s\n", asd_ha->hw_prof.pcba_sn);
 }
 static DEVICE_ATTR(pcba_sn, S_IRUGO, asd_show_dev_pcba_sn, NULL);
 
@@ -452,7 +451,7 @@  static ssize_t asd_show_update_bios(struct device *dev,
 	if (asd_ha->bios_status != FLASH_IN_PROGRESS)
 		asd_ha->bios_status = FLASH_OK;
 
-	return snprintf(buf, PAGE_SIZE, "status=%x %s\n",
+	return sysfs_emit(buf, "status=%x %s\n",
 			flash_error_table[i].err_code,
 			flash_error_table[i].reason);
 }
@@ -937,7 +936,7 @@  static int asd_scan_finished(struct Scsi_Host *shost, unsigned long time)
 
 static ssize_t version_show(struct device_driver *driver, char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%s\n", ASD_DRIVER_VERSION);
+	return sysfs_emit(buf, "%s\n", ASD_DRIVER_VERSION);
 }
 static DRIVER_ATTR_RO(version);