[ 109/143] isdnloop: several buffer overflows

Willy Tarreau
2014-05-12T01:42:45Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ 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>
---
drivers/isdn/isdnloop/isdnloop.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/isdn/isdnloop/isdnloop.c b/drivers/isdn/isdnloop/isdnloop.c
index 92d895f..bf4168b 100644
--- 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;
--
1.7.12.2.21.g234cd45.dirty