[PATCH v2] libselinux: avcstat: reject out-of-range interval values

[Evgeniy Gorbanyov <esgor@altlinux.org>]

strtoul() returns unsigned long, but avcstat stored the result in a
signed int and passed it to sleep(). A value above INT_MAX becomes
negative, and sleep() then treats it as a large unsigned duration.
Compare the full strtoul() result with INT_MAX before narrowing it.

Clear errno before strtoul() so a stale ERANGE cannot reject a valid
interval.

Signed-off-by: Evgeniy Gorbanyov <esgor@altlinux.org>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
---
 libselinux/utils/avcstat.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/libselinux/utils/avcstat.c b/libselinux/utils/avcstat.c
index 640a7a05..c7658792 100644
--- a/libselinux/utils/avcstat.c
+++ b/libselinux/utils/avcstat.c
@@ -13,6 +13,7 @@
 #include <libgen.h>
 #include <stdarg.h>
 #include <errno.h>
+#include <limits.h>
 #include <string.h>
 #include <fcntl.h>
 #include <unistd.h>
@@ -122,9 +123,12 @@ int main(int argc, char **argv)
 
 	if (optind < argc) {
 		char *arg = argv[optind];
-		unsigned int n = strtoul(arg, NULL, 10);
+		unsigned long n;
 
-		if (errno == ERANGE) {
+		errno = 0;
+		n = strtoul(arg, NULL, 10);
+
+		if (errno == ERANGE || n > INT_MAX) {
 			usage();
 			die("invalid interval \'%s\'", arg);
 		}
-- 
2.50.1