On Tue, Mar 16, 2021 at 05:02:34PM +0000, Luis Henriques wrote:
> When accidentally passing twice the same tag to qemu, kmemleak ended up
> reporting a memory leak in virtiofs. Also, looking at the log I saw the
> following error (that's when I realised the duplicated tag):
>
> virtiofs: probe of virtio5 failed with error -17
>
> Here's the kmemleak log for reference:
>
> unreferenced object 0xffff888103d47800 (size 1024):
> comm "systemd-udevd", pid 118, jiffies 4294893780 (age 18.340s)
> hex dump (first 32 bytes):
> 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N..........
> ff ff ff ff ff ff ff ff 80 90 02 a0 ff ff ff ff ................
> backtrace:
> [<000000000ebb87c1>] virtio_fs_probe+0x171/0x7ae [virtiofs]
> [<00000000f8aca419>] virtio_dev_probe+0x15f/0x210
> [<000000004d6baf3c>] really_probe+0xea/0x430
> [<00000000a6ceeac8>] device_driver_attach+0xa8/0xb0
> [<00000000196f47a7>] __driver_attach+0x98/0x140
> [<000000000b20601d>] bus_for_each_dev+0x7b/0xc0
> [<00000000399c7b7f>] bus_add_driver+0x11b/0x1f0
> [<0000000032b09ba7>] driver_register+0x8f/0xe0
> [<00000000cdd55998>] 0xffffffffa002c013
> [<000000000ea196a2>] do_one_initcall+0x64/0x2e0
> [<0000000008f727ce>] do_init_module+0x5c/0x260
> [<000000003cdedab6>] __do_sys_finit_module+0xb5/0x120
> [<00000000ad2f48c6>] do_syscall_64+0x33/0x40
> [<00000000809526b5>] entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Luis Henriques <lhenriques@xxxxxxx>
Hi Luis,
Thanks for the report and the fix. So looks like leak is happening
because we are not doing kfree(fs->vqs) in error path.
> ---
> fs/fuse/virtio_fs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
> index 8868ac31a3c0..4e6ef9f24e84 100644
> --- a/fs/fuse/virtio_fs.c
> +++ b/fs/fuse/virtio_fs.c
> @@ -899,7 +899,7 @@ static int virtio_fs_probe(struct virtio_device *vdev)
>
> out:
> vdev->priv = NULL;
> - kfree(fs);
> + virtio_fs_put(fs);
[ CC virtio-fs list ]
fs object is not fully formed. So calling virtio_fs_put() is little odd.
I will expect it to be called if somebody takes a reference using _get()
or in the final virtio_fs_remove() when creation reference should go
away.
How about open coding it and free fs->vqs explicitly. Something like
as follows.
@@ -896,7 +896,7 @@ static int virtio_fs_probe(struct virtio
out_vqs:
vdev->config->reset(vdev);
virtio_fs_cleanup_vqs(vdev, fs);
-
+ kfree(fs->vqs);
out:
vdev->priv = NULL;
kfree(fs);
Thanks
Vivek
