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perf: arm-ccn: Use scnprintf() for robustness 

snprintf() is a hard-to-use function, it's especially difficult to use
it for concatenating substrings in a buffer with a limited size.
Since snprintf() returns the would-be-output size, not the actual
size, the subsequent use of snprintf() may point to the incorrect
position easily.  Although the current code doesn't actually overflow
the buffer, it's an incorrect usage.

This patch replaces such snprintf() calls with a safer version,
scnprintf().

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Takashi Iwai 2020-03-15 10:37:15 +01:00 committed by Will Deacon
parent 29cc4ceeac
commit 06236821ae
1 changed files with 10 additions and 10 deletions
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20
drivers/perf/arm-ccn.c
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@ -328,15 +328,15 @@ static ssize_t arm_ccn_pmu_event_show(struct device *dev,
struct arm_ccn_pmu_event, attr);
ssize_t res;
res = snprintf(buf, PAGE_SIZE, "type=0x%x", event->type);
res = scnprintf(buf, PAGE_SIZE, "type=0x%x", event->type);
if (event->event)
res += snprintf(buf + res, PAGE_SIZE - res, ",event=0x%x",
res += scnprintf(buf + res, PAGE_SIZE - res, ",event=0x%x",
event->event);
if (event->def)
res += snprintf(buf + res, PAGE_SIZE - res, ",%s",
res += scnprintf(buf + res, PAGE_SIZE - res, ",%s",
event->def);
if (event->mask)
res += snprintf(buf + res, PAGE_SIZE - res, ",mask=0x%x",
res += scnprintf(buf + res, PAGE_SIZE - res, ",mask=0x%x",
event->mask);
/* Arguments required by an event */
@ -344,25 +344,25 @@ static ssize_t arm_ccn_pmu_event_show(struct device *dev,
case CCN_TYPE_CYCLES:
break;
case CCN_TYPE_XP:
res += snprintf(buf + res, PAGE_SIZE - res,
res += scnprintf(buf + res, PAGE_SIZE - res,
",xp=?,vc=?");
if (event->event == CCN_EVENT_WATCHPOINT)
res += snprintf(buf + res, PAGE_SIZE - res,
res += scnprintf(buf + res, PAGE_SIZE - res,
",port=?,dir=?,cmp_l=?,cmp_h=?,mask=?");
else
res += snprintf(buf + res, PAGE_SIZE - res,
res += scnprintf(buf + res, PAGE_SIZE - res,
",bus=?");
break;
case CCN_TYPE_MN:
res += snprintf(buf + res, PAGE_SIZE - res, ",node=%d", ccn->mn_id);
res += scnprintf(buf + res, PAGE_SIZE - res, ",node=%d", ccn->mn_id);
break;
default:
res += snprintf(buf + res, PAGE_SIZE - res, ",node=?");
res += scnprintf(buf + res, PAGE_SIZE - res, ",node=?");
break;
}
res += snprintf(buf + res, PAGE_SIZE - res, "\n");
res += scnprintf(buf + res, PAGE_SIZE - res, "\n");
return res;
}