isdn/capi: prevent NULL pointer dereference on invalid CAPI command
An invalid CAPI 2.0 command/subcommand combination may retrieve a
NULL pointer from the cpars[] array which will later be dereferenced
by the parser routines.
Fix by adding NULL pointer checks in strategic places.
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/isdn/capi/capiutil.c b/drivers/isdn/capi/capiutil.c
index 8e401ed..36835ef 100644
--- a/drivers/isdn/capi/capiutil.c
+++ b/drivers/isdn/capi/capiutil.c
@@ -318,6 +318,8 @@
cmsg->l = 8;
cmsg->p = 0;
cmsg->par = capi_cmd2par(cmsg->Command, cmsg->Subcommand);
+ if (!cmsg->par)
+ return 1; /* invalid command/subcommand */
pars_2_message(cmsg);
@@ -391,6 +393,8 @@
byteTRcpy(cmsg->m + 4, &cmsg->Command);
byteTRcpy(cmsg->m + 5, &cmsg->Subcommand);
cmsg->par = capi_cmd2par(cmsg->Command, cmsg->Subcommand);
+ if (!cmsg->par)
+ return 1; /* invalid command/subcommand */
message_2_pars(cmsg);
@@ -640,6 +644,9 @@
static _cdebbuf *protocol_message_2_pars(_cdebbuf *cdb, _cmsg *cmsg, int level)
{
+ if (!cmsg->par)
+ return NULL; /* invalid command/subcommand */
+
for (; TYP != _CEND; cmsg->p++) {
int slen = 29 + 3 - level;
int i;