2019-11-27 02:50:52

by Keita Suzuki

Subject: [PATCH] block/genhd: Fix memory leak in error path of __alloc_disk_node()

'disk->part_tbl' is malloced in disk_expand_part_tbl() and should be
freed before leaving from the error handling cases. However, current code
does not free this, causing a memory leak. Add disk_replace_part_tbl()
before freeing 'disk'.

I have tested this by randomly causing failures to the target code,
and verified on kmemleak that this memory leak does occur.

unreferenced object 0xffff888006dad500 (size 64):
comm "systemd-udevd", pid 116, jiffies 4294895558 (age 121.716s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<00000000eec79bf3>] disk_expand_part_tbl+0xab/0x170
[<00000000624e7d03>] __alloc_disk_node+0xb1/0x1c0
[<00000000ca3f4185>] 0xffffffffc01b8584
[<000000006f88a6ee>] do_one_initcall+0x8b/0x2a4
[<0000000016058199>] do_init_module+0xfd/0x380
[<00000000b6fde336>] load_module+0x3fae/0x4240
[<00000000c523d013>] __do_sys_finit_module+0x11a/0x1b0
[<00000000f07bba26>] do_syscall_64+0x6d/0x1e0
[<00000000979467fd>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Keita Suzuki <[email protected]>
---
block/genhd.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/block/genhd.c b/block/genhd.c
index ff6268970ddc..8c4b63d7f507 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1504,6 +1504,7 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
*/
seqcount_init(&disk->part0.nr_sects_seq);
if (hd_ref_init(&disk->part0)) {
+ disk_replace_part_tbl(disk, NULL);
hd_free_part(&disk->part0);
kfree(disk);
return NULL;
--
2.17.1

2019-12-04 09:57:04

by Naohiro Aota

Subject: Re: [PATCH] block/genhd: Fix memory leak in error path of __alloc_disk_node()

Looks good,
Reviewed-by: Naohiro Aota <[email protected]>

I think you can also add:

Fixes: 6c71013ecb7e ("block: partition: convert percpu ref")

On Wed, Nov 27, 2019 at 02:40:57AM +0000, Keita Suzuki wrote:
>'disk->part_tbl' is malloced in disk_expand_part_tbl() and should be
>freed before leaving from the error handling cases. However, current code
>does not free this, causing a memory leak. Add disk_replace_part_tbl()
>before freeing 'disk'.
>
>I have tested this by randomly causing failures to the target code,
>and verified on kmemleak that this memory leak does occur.
>
>unreferenced object 0xffff888006dad500 (size 64):
> comm "systemd-udevd", pid 116, jiffies 4294895558 (age 121.716s)
> hex dump (first 32 bytes):
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> backtrace:
> [<00000000eec79bf3>] disk_expand_part_tbl+0xab/0x170
> [<00000000624e7d03>] __alloc_disk_node+0xb1/0x1c0
> [<00000000ca3f4185>] 0xffffffffc01b8584
> [<000000006f88a6ee>] do_one_initcall+0x8b/0x2a4
> [<0000000016058199>] do_init_module+0xfd/0x380
> [<00000000b6fde336>] load_module+0x3fae/0x4240
> [<00000000c523d013>] __do_sys_finit_module+0x11a/0x1b0
> [<00000000f07bba26>] do_syscall_64+0x6d/0x1e0
> [<00000000979467fd>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
>Signed-off-by: Keita Suzuki <[email protected]>
>---
> block/genhd.c | 1 +
> 1 file changed, 1 insertion(+)
>
>diff --git a/block/genhd.c b/block/genhd.c
>index ff6268970ddc..8c4b63d7f507 100644
>--- a/block/genhd.c
>+++ b/block/genhd.c
>@@ -1504,6 +1504,7 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
> */
> seqcount_init(&disk->part0.nr_sects_seq);
> if (hd_ref_init(&disk->part0)) {
>+ disk_replace_part_tbl(disk, NULL);
> hd_free_part(&disk->part0);
> kfree(disk);
> return NULL;
>--
>2.17.1
>

2019-12-11 09:13:32

by Keita Suzuki

Subject: [PATCH RESEND] block/genhd: Fix memory leak in error path of __alloc_disk_node()

'disk->part_tbl' is malloced in disk_expand_part_tbl() and should be
freed before leaving from the error handling cases. However, current code
does not free this, causing a memory leak. Add disk_replace_part_tbl()
before freeing 'disk'.

I have tested this by randomly causing failures to the target code,
and verified on kmemleak that this memory leak does occur.

unreferenced object 0xffff888006dad500 (size 64):
comm "systemd-udevd", pid 116, jiffies 4294895558 (age 121.716s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<00000000eec79bf3>] disk_expand_part_tbl+0xab/0x170
[<00000000624e7d03>] __alloc_disk_node+0xb1/0x1c0
[<00000000ca3f4185>] 0xffffffffc01b8584
[<000000006f88a6ee>] do_one_initcall+0x8b/0x2a4
[<0000000016058199>] do_init_module+0xfd/0x380
[<00000000b6fde336>] load_module+0x3fae/0x4240
[<00000000c523d013>] __do_sys_finit_module+0x11a/0x1b0
[<00000000f07bba26>] do_syscall_64+0x6d/0x1e0
[<00000000979467fd>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 6c71013ecb7e ("block: partition: convert percpu ref")

Signed-off-by: Keita Suzuki <[email protected]>
Reviewed-by: Naohiro Aota <[email protected]>
---
block/genhd.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/block/genhd.c b/block/genhd.c
index ff6268970ddc..8c4b63d7f507 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1504,6 +1504,7 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
*/
seqcount_init(&disk->part0.nr_sects_seq);
if (hd_ref_init(&disk->part0)) {
+ disk_replace_part_tbl(disk, NULL);
hd_free_part(&disk->part0);
kfree(disk);
return NULL;
--
2.17.1