confile_utils: fix real-time signal parsing

Link: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=32521
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/confile_utils.c b/src/lxc/confile_utils.c
index e7516dc3916d7ed87c6a318dfdf86736be6e1da9..fc4f75433aab2ef2f5dc6970dcf3e57906a6769d 100644 (file)
--- a/src/lxc/confile_utils.c
+++ b/src/lxc/confile_utils.c
@@ -1024,17 +1024,31 @@ static int sig_num(const char *sig)
 
 static int rt_sig_num(const char *signame)
 {
-       int rtmax = 0, sig_n = 0;
+       bool rtmax;
+       int sig_n = 0;
 
-       if (strncasecmp(signame, "max-", 4) == 0)
-               rtmax = 1;
+       if (is_empty_string(signame))
+               return ret_errno(EINVAL);
+
+       if (strncasecmp(signame, "max-", STRLITERALLEN("max-")) == 0) {
+               rtmax = true;
+               signame += STRLITERALLEN("max-");
+       } else if (strncasecmp(signame, "min+", STRLITERALLEN("min+")) == 0) {
+               rtmax = false;
+               signame += STRLITERALLEN("min+");
+       } else {
+               return ret_errno(EINVAL);
+       }
 
-       signame += 4;
-       if (!isdigit(*signame))
+       if (is_empty_string(signame) || !isdigit(*signame))
                return ret_errno(EINVAL);
 
        sig_n = sig_num(signame);
-       sig_n = rtmax ? SIGRTMAX - sig_n : SIGRTMIN + sig_n;
+       if (rtmax)
+               sig_n = SIGRTMAX - sig_n;
+       else
+               sig_n = SIGRTMIN + sig_n;
+
        if (sig_n > SIGRTMAX || sig_n < SIGRTMIN)
                return ret_errno(EINVAL);
 
@@ -1043,16 +1057,15 @@ static int rt_sig_num(const char *signame)
 
 int sig_parse(const char *signame)
 {
-       size_t n;
-
-       if (isdigit(*signame)) {
+       if (isdigit(*signame))
                return sig_num(signame);
-       } else if (strncasecmp(signame, "sig", 3) == 0) {
-               signame += 3;
-               if (strncasecmp(signame, "rt", 2) == 0)
-                       return rt_sig_num(signame + 2);
 
-               for (n = 0; n < sizeof(signames) / sizeof((signames)[0]); n++)
+       if (strncasecmp(signame, "sig", STRLITERALLEN("sig")) == 0) {
+               signame += STRLITERALLEN("sig");
+               if (strncasecmp(signame, "rt", STRLITERALLEN("rt")) == 0)
+                       return rt_sig_num(signame + STRLITERALLEN("rt"));
+
+               for (size_t n = 0; n < ARRAY_SIZE(signames); n++)
                        if (strcasecmp(signames[n].name, signame) == 0)
                                return signames[n].num;
        }