On 04/08/07, James Bottomley <James.Bottomley@xxxxxxxxxxxx> wrote:
> On Sat, 2007-08-04 at 20:30 +0200, Jesper Juhl wrote:
> > (resend of patch previously submitted on 28-Jul-2007 23:06)
> >
> >
> > Ehlo,
> >
> > The Coverity checker noticed that we have a potential NULL pointer
> > deref in drivers/scsi/aic7xxx/aic7xxx_core.c::ahc_print_register().
> > This patch handles it by adding the same test against NULL that is
> > used elsewhere in the same function.
>
> It's on my list of things to look at ... but not very high. I suspect
> it actually isn't triggerable, but if you can tell me how, it will save
> me from looking.
>
Here's what Coverity reported :
...
6525 int
6526 ahc_print_register(ahc_reg_parse_entry_t *table, u_int num_entries,
6527 const char *name, u_int address, u_int value,
6528 u_int *cur_column, u_int wrap_point)
6529 {
6530 int printed;
6531 u_int printed_mask;
6532
Event var_compare_op: Added "cur_column" due to comparison "cur_column != 0"
Also see events: [var_deref_op]
At conditional (1): "cur_column != 0" taking false path
6533 if (cur_column != NULL && *cur_column >= wrap_point) {
6534 printf("\n");
6535 *cur_column = 0;
6536 }
6537 printed = printf("%s[0x%x]", name, value);
At conditional (2): "table == 0" taking true path
6538 if (table == NULL) {
6539 printed += printf(" ");
Event var_deref_op: Variable "cur_column" tracked as NULL was dereferenced.
Also see events: [var_compare_op]
6540 *cur_column += printed;
6541 return (printed);
6542 }
...
So it requires a NULL 'table' and a != NULL 'cur_column' to trigger.
Whether or not that's actually possible I'm not sure, but it seems
safer to guard against it :)
By the way; if this can actually be triggered, then
ahd_print_register() has the same problem.
--
Jesper Juhl <jesper.juhl@xxxxxxxxx>
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