[for-linus][PATCH 0/2] tracing: Two minor fixes

[for-linus][PATCH 0/2] tracing: Two minor fixes

[Steven Rostedt]

Two tracing fixes:

- Allow compares of strings when using signed and unsigned characters

- Fix kmemleak false positive for histogram entries.

Chen Jun (1):
      tracing: Fix a kmemleak false positive in tracing_map

Steven Rostedt (VMware) (1):
      tracing/histograms: String compares should not care about signed values

----
 kernel/trace/trace_events_hist.c | 2 +-
 kernel/trace/tracing_map.c       | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

[for-linus][PATCH 1/2] tracing/histograms: String compares should not care about signed values

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

When comparing two strings for the "onmatch" histogram trigger, fields
that are strings use string comparisons, which do not care about being
signed or not.

Do not fail to match two string fields if one is unsigned char array and
the other is a signed char array.

Link: https://lore.kernel.org/all/20211129123043.5cfd687a@gandalf.local.home/

Cc: stable@vgerk.kernel.org
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Yafang Shao <laoar.shao@gmail.com>
Fixes: b05e89ae7cf3b ("tracing: Accept different type for synthetic event fields")
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_events_hist.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 9555b8e1d1e3..319f9c8ca7e7 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -3757,7 +3757,7 @@ static int check_synth_field(struct synth_event *event,
 
 	if (strcmp(field->type, hist_field->type) != 0) {
 		if (field->size != hist_field->size ||
-		    field->is_signed != hist_field->is_signed)
+		    (!field->is_string && field->is_signed != hist_field->is_signed))
 			return -EINVAL;
 	}
 
-- 
2.33.0

[for-linus][PATCH 2/2] tracing: Fix a kmemleak false positive in tracing_map

[Steven Rostedt]

From: Chen Jun <chenjun102@huawei.com>

Doing the command:
  echo 'hist:key=common_pid.execname,common_timestamp' > /sys/kernel/debug/tracing/events/xxx/trigger

Triggers many kmemleak reports:

unreferenced object 0xffff0000c7ea4980 (size 128):
  comm "bash", pid 338, jiffies 4294912626 (age 9339.324s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000f3469921>] kmem_cache_alloc_trace+0x4c0/0x6f0
    [<0000000054ca40c3>] hist_trigger_elt_data_alloc+0x140/0x178
    [<00000000633bd154>] tracing_map_init+0x1f8/0x268
    [<000000007e814ab9>] event_hist_trigger_func+0xca0/0x1ad0
    [<00000000bf8520ed>] trigger_process_regex+0xd4/0x128
    [<00000000f549355a>] event_trigger_write+0x7c/0x120
    [<00000000b80f898d>] vfs_write+0xc4/0x380
    [<00000000823e1055>] ksys_write+0x74/0xf8
    [<000000008a9374aa>] __arm64_sys_write+0x24/0x30
    [<0000000087124017>] do_el0_svc+0x88/0x1c0
    [<00000000efd0dcd1>] el0_svc+0x1c/0x28
    [<00000000dbfba9b3>] el0_sync_handler+0x88/0xc0
    [<00000000e7399680>] el0_sync+0x148/0x180
unreferenced object 0xffff0000c7ea4980 (size 128):
  comm "bash", pid 338, jiffies 4294912626 (age 9339.324s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000f3469921>] kmem_cache_alloc_trace+0x4c0/0x6f0
    [<0000000054ca40c3>] hist_trigger_elt_data_alloc+0x140/0x178
    [<00000000633bd154>] tracing_map_init+0x1f8/0x268
    [<000000007e814ab9>] event_hist_trigger_func+0xca0/0x1ad0
    [<00000000bf8520ed>] trigger_process_regex+0xd4/0x128
    [<00000000f549355a>] event_trigger_write+0x7c/0x120
    [<00000000b80f898d>] vfs_write+0xc4/0x380
    [<00000000823e1055>] ksys_write+0x74/0xf8
    [<000000008a9374aa>] __arm64_sys_write+0x24/0x30
    [<0000000087124017>] do_el0_svc+0x88/0x1c0
    [<00000000efd0dcd1>] el0_svc+0x1c/0x28
    [<00000000dbfba9b3>] el0_sync_handler+0x88/0xc0
    [<00000000e7399680>] el0_sync+0x148/0x180

The reason is elts->pages[i] is alloced by get_zeroed_page.
and kmemleak will not scan the area alloced by get_zeroed_page.
The address stored in elts->pages will be regarded as leaked.

That is, the elts->pages[i] will have pointers loaded onto it as well, and
without telling kmemleak about it, those pointers will look like memory
without a reference.

To fix this, call kmemleak_alloc to tell kmemleak to scan elts->pages[i]

Link: https://lkml.kernel.org/r/20211124140801.87121-1-chenjun102@huawei.com

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/tracing_map.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c
index 39bb56d2dcbe..9628b5571846 100644
--- a/kernel/trace/tracing_map.c
+++ b/kernel/trace/tracing_map.c
@@ -15,6 +15,7 @@
 #include <linux/jhash.h>
 #include <linux/slab.h>
 #include <linux/sort.h>
+#include <linux/kmemleak.h>
 
 #include "tracing_map.h"
 #include "trace.h"
@@ -307,6 +308,7 @@ static void tracing_map_array_free(struct tracing_map_array *a)
 	for (i = 0; i < a->n_pages; i++) {
 		if (!a->pages[i])
 			break;
+		kmemleak_free(a->pages[i]);
 		free_page((unsigned long)a->pages[i]);
 	}
 
@@ -342,6 +344,7 @@ static struct tracing_map_array *tracing_map_array_alloc(unsigned int n_elts,
 		a->pages[i] = (void *)get_zeroed_page(GFP_KERNEL);
 		if (!a->pages[i])
 			goto free;
+		kmemleak_alloc(a->pages[i], PAGE_SIZE, 1, GFP_KERNEL);
 	}
  out:
 	return a;
-- 
2.33.0