2020-10-15 18:28:07

by Fedor Tokarev

Subject: [PATCH] tools: net: traceevent: Fix 'snprintf' return value check in 'tep_filter_strerror'

'snprintf' returns the number of characters which would have been written
if enough space had been available, excluding the terminating null byte.
Thus, the return value of 'buflen' means that the last character
was dropped.

Signed-off-by: Fedor Tokarev <[email protected]>
---
tools/lib/traceevent/parse-filter.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/traceevent/parse-filter.c b/tools/lib/traceevent/parse-filter.c
index c271aee..dccdbf2 100644
--- a/tools/lib/traceevent/parse-filter.c
+++ b/tools/lib/traceevent/parse-filter.c
@@ -1374,7 +1374,7 @@ int tep_filter_strerror(struct tep_event_filter *filter, enum tep_errno err,
if (strlen(filter->error_buffer) > 0) {
size_t len = snprintf(buf, buflen, "%s", filter->error_buffer);

- if (len > buflen)
+ if (len >= buflen)
return -1;
return 0;
}
--
2.7.4

2020-10-15 21:14:11

by walter harms

Subject: AW: [PATCH] tools: net: traceevent: Fix 'snprintf' return value check in 'tep_filter_strerror'

i guess the whole thing can be made more simple

we have len and buflen

len=strlen(filter->error_buffer);
if (len >= buflen )
return -1;

strcpy(buf, filter->error_buffer);

jm2c,


________________________________________
Von: Fedor Tokarev [[email protected]]
Gesendet: Donnerstag, 15. Oktober 2020 16:30
An: [email protected]; [email protected]
Cc: [email protected]; [email protected]; [email protected]
Betreff: [PATCH] tools: net: traceevent: Fix 'snprintf' return value check in 'tep_filter_strerror'

'snprintf' returns the number of characters which would have been written
if enough space had been available, excluding the terminating null byte.
Thus, the return value of 'buflen' means that the last character
was dropped.

Signed-off-by: Fedor Tokarev <[email protected]>
---
tools/lib/traceevent/parse-filter.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/traceevent/parse-filter.c b/tools/lib/traceevent/parse-filter.c
index c271aee..dccdbf2 100644
--- a/tools/lib/traceevent/parse-filter.c
+++ b/tools/lib/traceevent/parse-filter.c
@@ -1374,7 +1374,7 @@ int tep_filter_strerror(struct tep_event_filter *filter, enum tep_errno err,
if (strlen(filter->error_buffer) > 0) {
size_t len = snprintf(buf, buflen, "%s", filter->error_buffer);

- if (len > buflen)
+ if (len >= buflen)
return -1;
return 0;
}
--
2.7.4