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Subject[CHECKER] Questions about *_do_scsi & create_proc_entry

Hi,

I have a question about *_do_scsi(Scsi_Request *SRpnt, ...). If *SRpnt
is not NULL, *_do_scsi will not return NULL. I'm not quite sure about the
precondition in the following three 'errors' flaged by the NULL checker.
In these cases, can
*_do_scsi return NULL?

Another question is that by inspecting the NULL checker's result, I
found that *_do_scsi is always used in the following way "SRpnt =
*_do_scsi(SRPnt, ...)" no matther SRPnt is NULL or not. If SRpnt is not
NULL, why don't just use
*_do_scsi(SRPnt, ...);
The same thing happens to init_etherdev.

Last question: we found 3 potential errors in arch/i386/kernel. It
seems that create_proc_entry could return NULL. Please help us to verify
if they are bugs or not.

As usual, please CC us at mc@cs.stanford.edu. Any help will be
appreciated.

-Junfeng


---------------------------------------------------------
[UNKNOWN] osst_do_scsi will never return NULL if argument SRpnt isn't
NULL. But they copy SRpnt back by *aSRpnt, implies it could be NULL
/u2/acc/oses/linux/2.4.1/drivers/scsi/osst.c:1145:osst_read_back_buffer_and_rewrite:
ERROR:NULL:1042:1145: Using unknown ptr "SRpnt" illegally! set by
'osst_do_scsi':1042
for (i = 0, p = buffer; i < frames; i++, p += OS_DATA_SIZE) {
memset(cmd, 0, MAX_COMMAND_SIZE);
cmd[0] = 0x3C; /* Buffer Read */
cmd[1] = 6; /* Retrieve Faulty Block */
cmd[7] = 32768 >> 8;
cmd[8] = 32768 & 0xff;
Start --->
SRpnt = osst_do_scsi(SRpnt, STp, cmd, OS_FRAME_SIZE,
SCSI_DATA_READ,
STp->timeout, MAX_RETRIES,
TRUE);
if ((STp->buffer)->syscall_result) {
printk(KERN_ERR "osst%d: Failed to read block back
from OnStream buffer\n", dev);
vfree((void *)buffer);
*aSRpnt = SRpnt;
return (-EIO);
}
osst_copy_from_buffer(STp->buffer, p);
// memcpy(p, STp->buffer->b_data, OS_DATA_SIZE);
#if DEBUG
if (debugging)
printk(OSST_DEB_MSG "osst%d: Read back logical
block %d, data %x %x %x %x\n",
dev, logical_blk_num + i, p[0],
p[1], p[2], p[3]);
#endif
}
SRpnt is copied back
through *aSRpnt here
------>
*aSRpnt = SRpnt;
---------------------------------------------------------
[UNKNOWN]
/u2/acc/oses/linux/2.4.1/drivers/scsi/osst.c:1145:osst_read_back_buffer_and_rewrite:
ERROR:NULL:1111:1145: Using unknown ptr "SRpnt" illegally! set by
'osst_do_scsi':1111
---------------------------------------------------------
[UNKNOWN] osst_do_scsi can return NULL
/u2/acc/oses/linux/2.4.1/drivers/scsi/osst.c:1243:osst_reposition_and_retry:
ERROR:NULL:1237:1243: Using unknown ptr "SRpnt" illegally! set by
'osst_do_scsi':1237
#if DEBUG
printk(OSST_DEB_MSG "osst%d: About to write
pending lblk %d at frame %d\n",
dev, STp->logical_blk_num-1,
STp->first_frame_position);
#endif
Start--->
SRpnt = osst_do_scsi(SRpnt, STp, cmd,
OS_FRAME_SIZE, SCSI_DATA_WRITE,
STp->timeout,
MAX_WRITE_RETRIES, TRUE);

Copied back here --->
*aSRpnt = SRpnt;

if (STp->buffer->syscall_result) { /*
additional write error */
if ((SRpnt->sr_sense_buffer[ 2] & 0x0f) ==
13 &&
SRpnt->sr_sense_buffer[12] ==
0 &&
SRpnt->sr_sense_buffer[13] ==
2) {

---------------------------------------------------------
[UNKNOWN] create_proc_entry
/u2/acc/oses/linux/2.4.1/arch/i386/kernel/irq.c:1160:init_irq_proc:
ERROR:NULL:1158:1160: Using unknown ptr "entry" illegally! set by
'create_proc_entry':1158
root_irq_dir = proc_mkdir("irq", 0);

/* create /proc/irq/prof_cpu_mask */
Start-->
entry = create_proc_entry("prof_cpu_mask", 0600, root_irq_dir);
Error-->
entry->nlink = 1;
entry->data = (void *)&prof_cpu_mask;
entry->read_proc = prof_cpu_mask_read_proc;
entry->write_proc = prof_cpu_mask_write_proc;

---------------------------------------------------------
[UNKNOWN] create_proc_entry can return NULL
/u2/acc/oses/linux/2.4.1/arch/i386/kernel/irq.c:1139:register_irq_proc:
ERROR:NULL:1137:1139: Using unknown ptr "entry" illegally! set by
'create_proc_entry':1137
irq_dir[irq] = proc_mkdir(name, root_irq_dir);

/* create /proc/irq/1234/smp_affinity */
Start-->
entry = create_proc_entry("smp_affinity", 0600, irq_dir[irq]);
Error-->
entry->nlink = 1;
entry->data = (void *)(long)irq;
entry->read_proc = irq_affinity_read_proc;
---------------------------------------------------------
[UNKNOWN] create_proc_entry
/u2/acc/oses/linux/2.4.1/arch/i386/kernel/mtrr.c:2075:mtrr_init:
ERROR:NULL:2074:2075: Using unknown ptr "proc_root_mtrr" illegally! set by
'create_proc_entry':2074
#ifdef CONFIG_PROC_FS
Start-->
proc_root_mtrr = create_proc_entry ("mtrr", S_IWUSR | S_IRUGO,
&proc_root);
Error-->
proc_root_mtrr->owner = THIS_MODULE;
proc_root_mtrr->proc_fops = &mtrr_fops;
#endif
---------------------------------------------------------


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