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SubjectRe: [PATCH] fsm.c - null ptr fixes for 2.4.4
Date
We tried to minimize the amount of changes we made; your patch is far more 
extensive. As this is not our code, we felt it would be a bad idea to make
changes to the underlying structure.

Praveen Srinivasan and Frederick Akalin

Kai Germaschewski wrote:

> On Thu, 24 May 2001, Praveen Srinivasan wrote:
>
>> Using the Stanford checker, we searched for null-pointer bugs in the
>> linux kernel code. This patch fixes numerous unchecked pointers in the
>> ISDN hisax card driver (fsm.c).
>
> Is one numerous? Anyway, thanks for you effort. Your fix is not
> correct though, because it replaces the bug with another one.
>
> In case the allocation fails, the current code will oops directly, so it's
> quite easy to track down what went wrong. After applying your patch, the
> code will still oops, but at a later time, when one of the not correctly
> initialized state machines is actually used, so the problem is harder to
> track.
>
> The correct way to fix the problem is something along the lines of the
> appended patch. You need to notify the caller of the allocation failure
> and handle it correctly.
>
> Thanks for your work, I'll take care of submitting the right fix to Linus.
>
> --Kai
>
> Index: callc.c
> ===================================================================
> RCS file: /scratch/kai/cvsroot/linux_2_4/drivers/isdn/hisax/callc.c,v
> retrieving revision 1.1.1.2
> diff -u -r1.1.1.2 callc.c
> --- callc.c 2001/04/23 22:51:03 1.1.1.2
> +++ callc.c 2001/05/24 16:04:16
> @@ -850,14 +850,14 @@
>
> #define FNCOUNT (sizeof(fnlist)/sizeof(struct FsmNode))
>
> -void __init
> +int __init
> CallcNew(void)
> {
> callcfsm.state_count = STATE_COUNT;
> callcfsm.event_count = EVENT_COUNT;
> callcfsm.strEvent = strEvent;
> callcfsm.strState = strState;
> - FsmNew(&callcfsm, fnlist, FNCOUNT);
> + return FsmNew(&callcfsm, fnlist, FNCOUNT);
> }
>
> void
> Index: config.c
> ===================================================================
> RCS file: /scratch/kai/cvsroot/linux_2_4/drivers/isdn/hisax/config.c,v
> retrieving revision 1.1.1.4.32.1
> diff -u -r1.1.1.4.32.1 config.c
> --- config.c 2001/05/24 07:52:56 1.1.1.4.32.1
> +++ config.c 2001/05/24 16:17:00
> @@ -1332,18 +1332,28 @@
>
> static int __init HiSax_init(void)
> {
> - int i;
> + int i, retval;
> #ifdef MODULE
> int j;
> int nzproto = 0;
> #endif
>
> HiSaxVersion();
> - CallcNew();
> - Isdnl3New();
> - Isdnl2New();
> - TeiNew();
> - Isdnl1New();
> + retval = CallcNew();
> + if (retval)
> + goto out;
> + retval = Isdnl3New();
> + if (retval)
> + goto out_callc;
> + retval = Isdnl2New();
> + if (retval)
> + goto out_isdnl3;
> + retval = TeiNew();
> + if (retval)
> + goto out_isdnl2;
> + retval = Isdnl1New();
> + if (retval)
> + goto out_tei;
>
> #ifdef MODULE
> if (!type[0]) {
> @@ -1490,17 +1500,26 @@
> printk(KERN_DEBUG "HiSax: Total %d card%s defined\n",
> nrcards, (nrcards > 1) ? "s" : "");
>
> - if (HiSax_inithardware(NULL)) {
> - /* Install only, if at least one card found */
> - return (0);
> - } else {
> - Isdnl1Free();
> - TeiFree();
> - Isdnl2Free();
> - Isdnl3Free();
> - CallcFree();
> - return -EIO;
> + /* Install only, if at least one card found */
> + if (!HiSax_inithardware(NULL)) {
> + retval = -EIO;
> + goto out_isdnl1;
> }
> +
> + return 0;
> +
> + out_isdnl1:
> + Isdnl1Free();
> + out_tei:
> + TeiFree();
> + out_isdnl2:
> + Isdnl2Free();
> + out_isdnl3:
> + Isdnl3Free();
> + out_callc:
> + CallcFree();
> + out:
> + return retval;
> }
>
> static void __exit HiSax_exit(void)
> Index: fsm.c
> ===================================================================
> RCS file: /scratch/kai/cvsroot/linux_2_4/drivers/isdn/hisax/fsm.c,v
> retrieving revision 1.1.1.2
> diff -u -r1.1.1.2 fsm.c
> --- fsm.c 2001/04/23 22:51:00 1.1.1.2
> +++ fsm.c 2001/05/24 16:03:22
> @@ -15,13 +15,16 @@
>
> #define FSM_TIMER_DEBUG 0
>
> -void __init
> +int __init
> FsmNew(struct Fsm *fsm, struct FsmNode *fnlist, int fncount)
> {
> int i;
>
> fsm->jumpmatrix = (FSMFNPTR *)
> kmalloc(sizeof (FSMFNPTR) * fsm->state_count * fsm->event_count,
> GFP_KERNEL);
> + if (!fsm->jumpmatrix)
> + return -ENOMEM;
> +
> memset(fsm->jumpmatrix, 0, sizeof (FSMFNPTR) * fsm->state_count *
> fsm->event_count);
>
> for (i = 0; i < fncount; i++)
> @@ -32,6 +35,7 @@
> } else
> fsm->jumpmatrix[fsm->state_count * fnlist[i].event +
> fnlist[i].state] = (FSMFNPTR) fnlist[i].routine;
> + return 0;
> }
>
> void
> Index: hisax.h
> ===================================================================
> RCS file: /scratch/kai/cvsroot/linux_2_4/drivers/isdn/hisax/hisax.h,v
> retrieving revision 1.1.1.4
> diff -u -r1.1.1.4 hisax.h
> --- hisax.h 2001/04/24 00:23:56 1.1.1.4
> +++ hisax.h 2001/05/24 16:09:43
> @@ -1304,7 +1304,7 @@
> int getcallref(u_char * p);
> int newcallref(void);
>
> -void FsmNew(struct Fsm *fsm, struct FsmNode *fnlist, int fncount);
> +int FsmNew(struct Fsm *fsm, struct FsmNode *fnlist, int fncount);
> void FsmFree(struct Fsm *fsm);
> int FsmEvent(struct FsmInst *fi, int event, void *arg);
> void FsmChangeState(struct FsmInst *fi, int newstate);
> @@ -1335,19 +1335,19 @@
>
> int ll_run(struct IsdnCardState *cs, int addfeatures);
> void ll_stop(struct IsdnCardState *cs);
> -void CallcNew(void);
> +int CallcNew(void);
> void CallcFree(void);
> int CallcNewChan(struct IsdnCardState *cs);
> void CallcFreeChan(struct IsdnCardState *cs);
> -void Isdnl1New(void);
> +int Isdnl1New(void);
> void Isdnl1Free(void);
> -void Isdnl2New(void);
> +int Isdnl2New(void);
> void Isdnl2Free(void);
> -void Isdnl3New(void);
> +int Isdnl3New(void);
> void Isdnl3Free(void);
> void init_tei(struct IsdnCardState *cs, int protocol);
> void release_tei(struct IsdnCardState *cs);
> char *HiSax_getrev(const char *revision);
> -void TeiNew(void);
> +int TeiNew(void);
> void TeiFree(void);
> int certification_check(int output);
> Index: isdnl1.c
> ===================================================================
> RCS file: /scratch/kai/cvsroot/linux_2_4/drivers/isdn/hisax/isdnl1.c,v
> retrieving revision 1.1.1.2
> diff -u -r1.1.1.2 isdnl1.c
> --- isdnl1.c 2001/04/23 22:51:01 1.1.1.2
> +++ isdnl1.c 2001/05/24 16:06:14
> @@ -736,26 +736,41 @@
>
> #define L1B_FN_COUNT (sizeof(L1BFnList)/sizeof(struct FsmNode))
>
> -void __init
> +int __init
> Isdnl1New(void)
> {
> -#ifdef HISAX_UINTERFACE
> - l1fsm_u.state_count = L1U_STATE_COUNT;
> - l1fsm_u.event_count = L1_EVENT_COUNT;
> - l1fsm_u.strEvent = strL1Event;
> - l1fsm_u.strState = strL1UState;
> - FsmNew(&l1fsm_u, L1UFnList, L1U_FN_COUNT);
> -#endif
> + int retval;
> +
> l1fsm_s.state_count = L1S_STATE_COUNT;
> l1fsm_s.event_count = L1_EVENT_COUNT;
> l1fsm_s.strEvent = strL1Event;
> l1fsm_s.strState = strL1SState;
> - FsmNew(&l1fsm_s, L1SFnList, L1S_FN_COUNT);
> + retval = FsmNew(&l1fsm_s, L1SFnList, L1S_FN_COUNT);
> + if (retval)
> + return retval;
> +
> l1fsm_b.state_count = L1B_STATE_COUNT;
> l1fsm_b.event_count = L1_EVENT_COUNT;
> l1fsm_b.strEvent = strL1Event;
> l1fsm_b.strState = strL1BState;
> - FsmNew(&l1fsm_b, L1BFnList, L1B_FN_COUNT);
> + retval = FsmNew(&l1fsm_b, L1BFnList, L1B_FN_COUNT);
> + if (retval) {
> + FsmFree(&l1fsm_s);
> + return retval;
> + }
> +#ifdef HISAX_UINTERFACE
> + l1fsm_u.state_count = L1U_STATE_COUNT;
> + l1fsm_u.event_count = L1_EVENT_COUNT;
> + l1fsm_u.strEvent = strL1Event;
> + l1fsm_u.strState = strL1UState;
> + retval = FsmNew(&l1fsm_u, L1UFnList, L1U_FN_COUNT);
> + if (retval) {
> + FsmFree(&l1fsm_s);
> + FsmFree(&l1fsm_b);
> + return retval;
> + }
> +#endif
> + return 0;
> }
>
> void Isdnl1Free(void)
> Index: isdnl2.c
> ===================================================================
> RCS file: /scratch/kai/cvsroot/linux_2_4/drivers/isdn/hisax/isdnl2.c,v
> retrieving revision 1.1.1.2
> diff -u -r1.1.1.2 isdnl2.c
> --- isdnl2.c 2001/04/23 22:51:01 1.1.1.2
> +++ isdnl2.c 2001/05/24 16:06:36
> @@ -1831,14 +1831,14 @@
> {
> }
>
> -void __init
> +int __init
> Isdnl2New(void)
> {
> l2fsm.state_count = L2_STATE_COUNT;
> l2fsm.event_count = L2_EVENT_COUNT;
> l2fsm.strEvent = strL2Event;
> l2fsm.strState = strL2State;
> - FsmNew(&l2fsm, L2FnList, L2_FN_COUNT);
> + return FsmNew(&l2fsm, L2FnList, L2_FN_COUNT);
> }
>
> void
> Index: isdnl3.c
> ===================================================================
> RCS file: /scratch/kai/cvsroot/linux_2_4/drivers/isdn/hisax/isdnl3.c,v
> retrieving revision 1.1.1.2
> diff -u -r1.1.1.2 isdnl3.c
> --- isdnl3.c 2001/04/23 22:51:01 1.1.1.2
> +++ isdnl3.c 2001/05/24 16:07:16
> @@ -591,14 +591,14 @@
> }
> }
>
> -void __init
> +int __init
> Isdnl3New(void)
> {
> l3fsm.state_count = L3_STATE_COUNT;
> l3fsm.event_count = L3_EVENT_COUNT;
> l3fsm.strEvent = strL3Event;
> l3fsm.strState = strL3State;
> - FsmNew(&l3fsm, L3FnList, L3_FN_COUNT);
> + return FsmNew(&l3fsm, L3FnList, L3_FN_COUNT);
> }
>
> void
> Index: tei.c
> ===================================================================
> RCS file: /scratch/kai/cvsroot/linux_2_4/drivers/isdn/hisax/tei.c,v
> retrieving revision 1.1.1.2
> diff -u -r1.1.1.2 tei.c
> --- tei.c 2001/04/23 22:51:00 1.1.1.2
> +++ tei.c 2001/05/24 16:07:11
> @@ -446,14 +446,14 @@
>
> #define TEI_FN_COUNT (sizeof(TeiFnList)/sizeof(struct FsmNode))
>
> -void __init
> +int __init
> TeiNew(void)
> {
> teifsm.state_count = TEI_STATE_COUNT;
> teifsm.event_count = TEI_EVENT_COUNT;
> teifsm.strEvent = strTeiEvent;
> teifsm.strState = strTeiState;
> - FsmNew(&teifsm, TeiFnList, TEI_FN_COUNT);
> + return FsmNew(&teifsm, TeiFnList, TEI_FN_COUNT);
> }
>
> void
>
> -
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