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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>
This commit is contained in:
Tilman Schmidt 2014-10-11 13:46:30 +02:00 committed by David S. Miller
parent 854d23b77a
commit 5510ab1804
1 changed files with 7 additions and 0 deletions
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7
drivers/isdn/capi/capiutil.c
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@ -318,6 +318,8 @@ unsigned capi_cmsg2message(_cmsg *cmsg, u8 *msg)
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 @@ unsigned capi_message2cmsg(_cmsg *cmsg, u8 *msg)
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 *printstruct(_cdebbuf *cdb, u8 *m)
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;