isdn: strcpy() => strlcpy()

setup.phone and setup.eazmsn are 32 character buffers.
rcvmsg.msg_data.byte_array is a 48 character buffer.
sc_adapter[card]->channel[rcvmsg.phy_link_no - 1].dn is 50 chars.

The rcvmsg struct comes from the memcpy_fromio() in receivemessage().
I guess that means it's data off the wire.  I'm not very familiar with
this code but I don't see any reason to assume these strings are NULL
terminated.

Also it's weird that "dn" in a 50 character buffer but we only seem to
use 32 characters.  In drivers/isdn/sc/scioc.h, "dn" is only a 49
character buffer.  So potentially there is still an issue there.

The important thing for now is to prevent the memory corruption.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 4 deletions

diff --git a/drivers/isdn/sc/interrupt.c b/drivers/isdn/sc/interrupt.c
index 485be8b1e1b3..f0225bc0f267 100644
--- a/drivers/isdn/sc/interrupt.c
+++ b/drivers/isdn/sc/interrupt.c
@@ -112,11 +112,19 @@ irqreturn_t interrupt_handler(int dummy, void *card_inst)
                         }
                         else if(callid>=0x0000 && callid<=0x7FFF)
                         {
+                                int len;
+
                                 pr_debug("%s: Got Incoming Call\n",
                                                 sc_adapter[card]->devicename);
-                                strcpy(setup.phone,&(rcvmsg.msg_data.byte_array[4]));
-                                strcpy(setup.eazmsn,
-                                        sc_adapter[card]->channel[rcvmsg.phy_link_no-1].dn);
+                                len = strlcpy(setup.phone, &(rcvmsg.msg_data.byte_array[4]),
+                                                sizeof(setup.phone));
+                                if (len >= sizeof(setup.phone))
+                                        continue;
+                                len = strlcpy(setup.eazmsn,
+                                                sc_adapter[card]->channel[rcvmsg.phy_link_no - 1].dn,
+                                                sizeof(setup.eazmsn));
+                                if (len >= sizeof(setup.eazmsn))
+                                        continue;
                                 setup.si1 = 7;
                                 setup.si2 = 0;
                                 setup.plan = 0;
@@ -176,7 +184,9 @@ irqreturn_t interrupt_handler(int dummy, void *card_inst)
                  * Handle a GetMyNumber Rsp
                  */
                 if (IS_CE_MESSAGE(rcvmsg,Call,0,GetMyNumber)){
-                        strcpy(sc_adapter[card]->channel[rcvmsg.phy_link_no-1].dn,rcvmsg.msg_data.byte_array);
+                        strlcpy(sc_adapter[card]->channel[rcvmsg.phy_link_no - 1].dn,
+                                rcvmsg.msg_data.byte_array,
+                                sizeof(rcvmsg.msg_data.byte_array));
                         continue;
                 }