Vivek Goyal vgoyal@redhat.com writes:
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@vger.kernel.org Signed-off-by: Luis Henriques lhenriques@suse.de
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.
Yep!
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 ]
Oops, forgot to include it. Maybe it should be added to the MAINTAINERS file (although IIRC it's not an open 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.
Ok, I'll send v2 later (I'm currently away from my devel workstation). To be honest, my initial version was doing exactly what you're suggesting. I decided to change to virtio_fs_put() because the refcount was already initialised early in the function. Bad decision.
Cheers,