isdnloop: several buffer overflows

[ Upstream commit 7563487cbf865284dcd35e9ef5a95380da046737 ]

There are three buffer overflows addressed in this patch.

1) In isdnloop_fake_err() we add an 'E' to a 60 character string and
then copy it into a 60 character buffer.  I have made the destination
buffer 64 characters and I'm changed the sprintf() to a snprintf().

2) In isdnloop_parse_cmd(), p points to a 6 characters into a 60
character buffer so we have 54 characters.  The ->eazlist[] is 11
characters long.  I have modified the code to return if the source
buffer is too long.

3) In isdnloop_command() the cbuf[] array was 60 characters long but the
max length of the string then can be up to 79 characters.  I made the
cbuf array 80 characters long and changed the sprintf() to snprintf().
I also removed the temporary "dial" buffer and changed it to use "p"
directly.

Unfortunately, we pass the "cbuf" string from isdnloop_command() to
isdnloop_writecmd() which truncates anything over 60 characters to make
it fit in card->omsg[].  (It can accept values up to 255 characters so
long as there is a '\n' character every 60 characters).  For now I have
just fixed the memory corruption bug and left the other problems in this
driver alone.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/drivers/isdn/isdnloop/isdnloop.c b/drivers/isdn/isdnloop/isdnloop.c
index 92d895f282a74c31b237da98113bb8b9dba29318..bf4168bb0ca024806cf9ac03dcf88179e54e79c5 100644 (file)
--- a/drivers/isdn/isdnloop/isdnloop.c
+++ b/drivers/isdn/isdnloop/isdnloop.c
@@ -517,9 +517,9 @@ static isdnloop_stat isdnloop_cmd_table[] =
 static void
 isdnloop_fake_err(isdnloop_card * card)
 {
-       char buf[60];
+       char buf[64];
 
-       sprintf(buf, "E%s", card->omsg);
+       snprintf(buf, sizeof(buf), "E%s", card->omsg);
        isdnloop_fake(card, buf, -1);
        isdnloop_fake(card, "NAK", -1);
 }
@@ -902,6 +902,8 @@ isdnloop_parse_cmd(isdnloop_card * card)
                case 7:
                        /* 0x;EAZ */
                        p += 3;
+                       if (strlen(p) >= sizeof(card->eazlist[0]))
+                               break;
                        strcpy(card->eazlist[ch - 1], p);
                        break;
                case 8:
@@ -1126,7 +1128,7 @@ isdnloop_command(isdn_ctrl * c, isdnloop_card * card)
 {
        ulong a;
        int i;
-       char cbuf[60];
+       char cbuf[80];
        isdn_ctrl cmd;
        isdnloop_cdef cdef;
 
@@ -1191,7 +1193,6 @@ isdnloop_command(isdn_ctrl * c, isdnloop_card * card)
                                break;
                        if ((c->arg & 255) < ISDNLOOP_BCH) {
                                char *p;
-                               char dial[50];
                                char dcode[4];
 
                                a = c->arg;
@@ -1203,10 +1204,10 @@ isdnloop_command(isdn_ctrl * c, isdnloop_card * card)
                                } else
                                        /* Normal Dial */
                                        strcpy(dcode, "CAL");
-                               strcpy(dial, p);
-                               sprintf(cbuf, "%02d;D%s_R%s,%02d,%02d,%s\n", (int) (a + 1),
-                                       dcode, dial, c->parm.setup.si1,
-                               c->parm.setup.si2, c->parm.setup.eazmsn);
+                               snprintf(cbuf, sizeof(cbuf),
+                                        "%02d;D%s_R%s,%02d,%02d,%s\n", (int) (a + 1),
+                                        dcode, p, c->parm.setup.si1,
+                                        c->parm.setup.si2, c->parm.setup.eazmsn);
                                i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
                        }
                        break;