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thermal: sysfs: Use sysfs_emit_at() in trans_table_show()

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Replace snprintf() with sysfs_emit_at() in trans_table_show().
sysfs_emit_at() is preferred for formatting sysfs output because it
provides safer bounds checking.

Convert multiple PAGE_SIZE length checks to check the number of bytes
actually copied by sysfs_emit_at(), thus avoiding manual buffer size
accounting.

Consistently return -EFBIG when the transition table output exceeds the
sysfs buffer, including the header row.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://patch.msgid.link/20260719132251.31936-3-thorsten.blum@linux.dev
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Thorsten Blum 2026-07-19 15:22:53 +02:00 committed by Rafael J. Wysocki
parent 1590cf0329
commit de8e50af88
1 changed files with 24 additions and 25 deletions
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49
drivers/thermal/thermal_sysfs.c
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@ -706,7 +706,7 @@ static ssize_t trans_table_show(struct device *dev,
struct thermal_cooling_device *cdev = to_cooling_device(dev);
struct cooling_dev_stats *stats;
ssize_t len = 0;
int i, j;
int i, j, copied;
guard(cooling_dev)(cdev);
@ -714,41 +714,40 @@ static ssize_t trans_table_show(struct device *dev,
if (!stats)
return -ENODATA;
len += snprintf(buf + len, PAGE_SIZE - len, " From : To\n");
len += snprintf(buf + len, PAGE_SIZE - len, " : ");
len += sysfs_emit_at(buf, len, " From : To\n");
len += sysfs_emit_at(buf, len, " : ");
for (i = 0; i <= cdev->max_state; i++) {
if (len >= PAGE_SIZE)
break;
len += snprintf(buf + len, PAGE_SIZE - len, "state%2u ", i);
copied = sysfs_emit_at(buf, len, "state%2u ", i);
if (!copied)
goto buf_full;
len += copied;
}
if (len >= PAGE_SIZE)
return PAGE_SIZE;
len += snprintf(buf + len, PAGE_SIZE - len, "\n");
len += sysfs_emit_at(buf, len, "\n");
for (i = 0; i <= cdev->max_state; i++) {
if (len >= PAGE_SIZE)
break;
len += snprintf(buf + len, PAGE_SIZE - len, "state%2u:", i);
copied = sysfs_emit_at(buf, len, "state%2u:", i);
if (!copied)
goto buf_full;
len += copied;
for (j = 0; j <= cdev->max_state; j++) {
if (len >= PAGE_SIZE)
break;
len += snprintf(buf + len, PAGE_SIZE - len, "%8u ",
copied = sysfs_emit_at(buf, len, "%8u ",
stats->trans_table[i * (cdev->max_state + 1) + j]);
if (!copied)
goto buf_full;
len += copied;
}
if (len >= PAGE_SIZE)
break;
len += snprintf(buf + len, PAGE_SIZE - len, "\n");
}
if (len >= PAGE_SIZE) {
pr_warn_once("Thermal transition table exceeds PAGE_SIZE. Disabling\n");
len = -EFBIG;
copied = sysfs_emit_at(buf, len, "\n");
if (!copied)
goto buf_full;
len += copied;
}
return len;
buf_full:
pr_warn_once("Thermal transition table exceeds PAGE_SIZE. Disabling\n");
return -EFBIG;
}
static DEVICE_ATTR_RO(total_trans);