tty: nozomi: Use scnprintf() for avoiding potential buffer overflow

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit.  Fix it by replacing with scnprintf().

Also rewrite the code in a standard if-form instead of ugly
conditional operators.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20200311092905.24362-1-tiwai@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/nozomi.c b/drivers/tty/nozomi.c
index 4b82ec30c78990453403f04bb021220ac3e7cbdb..d42b854cb7df2b08227ebf4cba001615a8a2a0d3 100644 (file)
--- a/drivers/tty/nozomi.c
+++ b/drivers/tty/nozomi.c
@@ -839,40 +839,39 @@ static char *interrupt2str(u16 interrupt)
        static char buf[TMP_BUF_MAX];
        char *p = buf;
 
-       interrupt & MDM_DL1 ? p += snprintf(p, TMP_BUF_MAX, "MDM_DL1 ") : NULL;
-       interrupt & MDM_DL2 ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "MDM_DL2 ") : NULL;
-
-       interrupt & MDM_UL1 ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "MDM_UL1 ") : NULL;
-       interrupt & MDM_UL2 ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "MDM_UL2 ") : NULL;
-
-       interrupt & DIAG_DL1 ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "DIAG_DL1 ") : NULL;
-       interrupt & DIAG_DL2 ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "DIAG_DL2 ") : NULL;
-
-       interrupt & DIAG_UL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "DIAG_UL ") : NULL;
-
-       interrupt & APP1_DL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "APP1_DL ") : NULL;
-       interrupt & APP2_DL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "APP2_DL ") : NULL;
-
-       interrupt & APP1_UL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "APP1_UL ") : NULL;
-       interrupt & APP2_UL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "APP2_UL ") : NULL;
-
-       interrupt & CTRL_DL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "CTRL_DL ") : NULL;
-       interrupt & CTRL_UL ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "CTRL_UL ") : NULL;
-
-       interrupt & RESET ? p += snprintf(p, TMP_BUF_MAX - (p - buf),
-                                       "RESET ") : NULL;
+       if (interrupt & MDM_DL1)
+               p += scnprintf(p, TMP_BUF_MAX, "MDM_DL1 ");
+       if (interrupt & MDM_DL2)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "MDM_DL2 ");
+       if (interrupt & MDM_UL1)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "MDM_UL1 ");
+       if (interrupt & MDM_UL2)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "MDM_UL2 ");
+       if (interrupt & DIAG_DL1)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "DIAG_DL1 ");
+       if (interrupt & DIAG_DL2)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "DIAG_DL2 ");
+
+       if (interrupt & DIAG_UL)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "DIAG_UL ");
+
+       if (interrupt & APP1_DL)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "APP1_DL ");
+       if (interrupt & APP2_DL)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "APP2_DL ");
+
+       if (interrupt & APP1_UL)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "APP1_UL ");
+       if (interrupt & APP2_UL)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "APP2_UL ");
+
+       if (interrupt & CTRL_DL)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "CTRL_DL ");
+       if (interrupt & CTRL_UL)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "CTRL_UL ");
+
+       if (interrupt & RESET)
+               p += scnprintf(p, TMP_BUF_MAX - (p - buf), "RESET ");
 
        return buf;
 }