debug_sprintf_event calls __debug_sprintf_event
with a format and arguments.
There various types of arguments used in these
call, but __debug_sprintf_event uses va_arg
with only long as the type argument so random
errors could occur because the type and argument
are supposed to match.
debug_entry_t *__debug_sprintf_event(debug_info_t *id, int level, char *string, ...)
{
[...]
va_start(ap, string);
curr_event->string = string;
for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
curr_event->args[idx] = va_arg(ap, long);
va_end(ap);
[...]
}
from man va_arg
va_arg()
if type is not compatible with the type of the actual next argument
(as promoted according to the default argument promotions),
random errors will occur.
For instance, uses like:
arch/s390/kernel/perf_cpum_sf.c:919: debug_sprintf_event(sfdbg, 6, "pmu_enable: es=%i cs=%i ed=%i cd=%i "
arch/s390/kernel/perf_cpum_sf.c-920- "tear=%p dear=%p\n", cpuhw->lsctl.es, cpuhw->lsctl.cs,
arch/s390/kernel/perf_cpum_sf.c-921- cpuhw->lsctl.ed, cpuhw->lsctl.cd,
arch/s390/kernel/perf_cpum_sf.c-922- (void *) cpuhw->lsctl.tear, (void *) cpuhw->lsctl.dear);
where the first 3 arguments are int but their type
as used by va_arg in __debug_sprintf_event is long
which could produce random errors.
Instead of adding complete format % decoding,
perhaps the easiest solution is to change all
the formats to use %lu or %ld and cast each
argument as appropriate.
And I found this when looking at another defect
in debug_sprintf_event where a %p<foo> extension
is unintentionally used via a string concatenation.
as pointed out by Rasmus Villemoes
---
arch/s390/kernel/perf_cpum_sf.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
index 1c9ddd7aa5ec..1c449a6f841a 100644
--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -212,9 +212,7 @@ static int realloc_sampling_buffer(struct sf_buffer *sfb,
* the sampling buffer origin.
*/
if (sfb->sdbt != get_next_sdbt(tail)) {
- debug_sprintf_event(sfdbg, 3, "realloc_sampling_buffer: "
- "sampling buffer is not linked: origin=%p"
- "tail=%p\n",
+ debug_sprintf_event(sfdbg, 3, "realloc_sampling_buffer: sampling buffer is not linked: origin=%p tail=%p\n",
(void *) sfb->sdbt, (void *) tail);
return -EINVAL;
}
--
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