Fixed out of boundary write on long lines.

The terminating nul character ('\0') could be written outside the boundary of
the buffer which is used to read characters. If "sizeof(buffer)" characters
are read, the resulting value must not be used as index, because that's an off
by one.

Read sizeof(buffer)-1 bytes instead.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/slstatus.c b/slstatus.c
index 90b4808..6deb68c 100644
--- a/slstatus.c
+++ b/slstatus.c
@@ -447,9 +447,9 @@ run_command(const char *cmd)
 		warn("Failed to get command output for %s", cmd);
 		return smprintf("%s", UNKNOWN_STR);
 	}
-	fgets(buf, sizeof(buf), fp);
+	fgets(buf, sizeof(buf) - 1, fp);
 	pclose(fp);
-	buf[sizeof(buf)] = '\0';
+	buf[sizeof(buf) - 1] = '\0';
 
 	if ((nlptr = strstr(buf, "\n")) != NULL) {
 		nlptr[0] = '\0';
@@ -473,7 +473,7 @@ swap_free(void)
 		return smprintf("%s", UNKNOWN_STR);
 	}
 
-	if ((bytes_read = fread(buf, sizeof(char), sizeof(buf), fp)) == 0) {
+	if ((bytes_read = fread(buf, sizeof(char), sizeof(buf) - 1, fp)) == 0) {
 		warn("swap_free: read error");
 		fclose(fp);
 		return smprintf("%s", UNKNOWN_STR);
@@ -510,7 +510,7 @@ swap_perc(void)
 		return smprintf("%s", UNKNOWN_STR);
 	}
 
-	if ((bytes_read = fread(buf, sizeof(char), sizeof(buf), fp)) == 0) {
+	if ((bytes_read = fread(buf, sizeof(char), sizeof(buf) - 1, fp)) == 0) {
 		warn("swap_perc: read error");
 		fclose(fp);
 		return smprintf("%s", UNKNOWN_STR);
@@ -551,7 +551,7 @@ swap_total(void)
 		warn("Failed to open file /proc/meminfo");
 		return smprintf("%s", UNKNOWN_STR);
 	}
-	if ((bytes_read = fread(buf, sizeof(char), sizeof(buf), fp)) == 0) {
+	if ((bytes_read = fread(buf, sizeof(char), sizeof(buf) - 1, fp)) == 0) {
 		warn("swap_total: read error");
 		fclose(fp);
 		return smprintf("%s", UNKNOWN_STR);
@@ -582,7 +582,7 @@ swap_used(void)
 		warn("Failed to open file /proc/meminfo");
 		return smprintf("%s", UNKNOWN_STR);
 	}
-	if ((bytes_read = fread(buf, sizeof(char), sizeof(buf), fp)) == 0) {
+	if ((bytes_read = fread(buf, sizeof(char), sizeof(buf) - 1, fp)) == 0) {
 		warn("swap_used: read error");
 		fclose(fp);
 		return smprintf("%s", UNKNOWN_STR);