Hi Jinjie, Jonathan,
On 12/10/2024 19:15, Jonathan Cameron wrote:
On Fri, 11 Oct 2024 17:55:12 +0800
Jinjie Ruan <ruanjinjie@xxxxxxxxxx> wrote:
modprobe iio-test-gts and rmmod it, then the following memory leak
occurs:
unreferenced object 0xffffff80c810be00 (size 64):
comm "kunit_try_catch", pid 1654, jiffies 4294913981
hex dump (first 32 bytes):
02 00 00 00 08 00 00 00 20 00 00 00 40 00 00 00 ........ ...@...
80 00 00 00 00 02 00 00 00 04 00 00 00 08 00 00 ................
backtrace (crc a63d875e):
[<0000000028c1b3c2>] kmemleak_alloc+0x34/0x40
[<000000001d6ecc87>] __kmalloc_noprof+0x2bc/0x3c0
[<00000000393795c1>] devm_iio_init_iio_gts+0x4b4/0x16f4
[<0000000071bb4b09>] 0xffffffdf052a62e0
[<000000000315bc18>] 0xffffffdf052a6488
[<00000000f9dc55b5>] kunit_try_run_case+0x13c/0x3ac
[<00000000175a3fd4>] kunit_generic_run_threadfn_adapter+0x80/0xec
[<00000000f505065d>] kthread+0x2e8/0x374
[<00000000bbfb0e5d>] ret_from_fork+0x10/0x20
unreferenced object 0xffffff80cbfe9e70 (size 16):
comm "kunit_try_catch", pid 1658, jiffies 4294914015
hex dump (first 16 bytes):
10 00 00 00 40 00 00 00 80 00 00 00 00 00 00 00 ....@...........
backtrace (crc 857f0cb4):
[<0000000028c1b3c2>] kmemleak_alloc+0x34/0x40
[<000000001d6ecc87>] __kmalloc_noprof+0x2bc/0x3c0
[<00000000393795c1>] devm_iio_init_iio_gts+0x4b4/0x16f4
[<0000000071bb4b09>] 0xffffffdf052a62e0
[<000000007d089d45>] 0xffffffdf052a6864
[<00000000f9dc55b5>] kunit_try_run_case+0x13c/0x3ac
[<00000000175a3fd4>] kunit_generic_run_threadfn_adapter+0x80/0xec
[<00000000f505065d>] kthread+0x2e8/0x374
[<00000000bbfb0e5d>] ret_from_fork+0x10/0x20
......
It includes 5*5 times "size 64" memory leaks, which correspond to 5 times
test_init_iio_gain_scale() calls with gts_test_gains size 10 (10*size(int))
and gts_test_itimes size 5. It also includes 5*1 times "size 16"
memory leak, which correspond to one time __test_init_iio_gain_scale()
call with gts_test_gains_gain_low size 3 (3*size(int)) and gts_test_itimes
size 5.
The reason is that the per_time_gains[i] is not freed which is allocated in
the "gts->num_itime" for loop in iio_gts_build_avail_scale_table().
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 38416c28e168 ("iio: light: Add gain-time-scale helpers")
Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
Hi Jinjie,
Your explanation looks correct to me. I'll wait a while though to give Matti time
to take a look as well.
Sorry for late reply - I spent last couple of days walking through the
swamps and forests in the wilderness.
Something was bothering me with this. I browsed through the code and all
the allocations and I'm not able to see why these arrays shouldn't be
freed. I did even go through the versions I've sent on list trying to
find out what bothers me.
Well, I found nothing. The version 2 had some code which looped through
these arrays freeing them - in an error path - but not in successful
case. It seemed as if I had thought these values had to be maintained -
but I really can't see why.
So - thanks. I suppose leaving the memory not freed is just a bug :)
Nice that you killed this one :)
Reviewed-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
Thanks,
Jonathan
---
drivers/iio/industrialio-gts-helper.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/iio/industrialio-gts-helper.c b/drivers/iio/industrialio-gts-helper.c
index 59d7615c0f56..7326c7949244 100644
--- a/drivers/iio/industrialio-gts-helper.c
+++ b/drivers/iio/industrialio-gts-helper.c
@@ -307,6 +307,8 @@ static int iio_gts_build_avail_scale_table(struct iio_gts *gts)
if (ret)
goto err_free_out;
+ for (i = 0; i < gts->num_itime; i++)
+ kfree(per_time_gains[i]);
kfree(per_time_gains);
gts->per_time_avail_scale_tables = per_time_scales;
