| Message ID | 164505751190.4175768.13324905271463416712.stgit@dwillia2-desk3.amr.corp.intel.com |
|---|---|
| State | Accepted |
| Commit | 74be98774dfbc5b8b795db726bd772e735d2edd4 |
| Headers | show |
| Series | cxl/port: Hold port reference until decoder release | expand |
On 22-02-16 16:25:11, Dan Williams wrote: > KASAN + DEBUG_KOBJECT_RELEASE reports a potential use-after-free in > cxl_decoder_release() where it goes to reference its parent, a cxl_port, > to free its id back to port->decoder_ida. > > BUG: KASAN: use-after-free in to_cxl_port+0x18/0x90 [cxl_core] > Read of size 8 at addr ffff888119270908 by task kworker/35:2/379 > > CPU: 35 PID: 379 Comm: kworker/35:2 Tainted: G OE 5.17.0-rc2+ #198 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 > Workqueue: events kobject_delayed_cleanup > Call Trace: > <TASK> > dump_stack_lvl+0x59/0x73 > print_address_description.constprop.0+0x1f/0x150 > ? to_cxl_port+0x18/0x90 [cxl_core] > kasan_report.cold+0x83/0xdf > ? to_cxl_port+0x18/0x90 [cxl_core] > to_cxl_port+0x18/0x90 [cxl_core] > cxl_decoder_release+0x2a/0x60 [cxl_core] > device_release+0x5f/0x100 > kobject_cleanup+0x80/0x1c0 > > The device core only guarantees parent lifetime until all children are > unregistered. If a child needs a parent to complete its ->release() > callback that child needs to hold a reference to extend the lifetime of > the parent. > > Fixes: 40ba17afdfab ("cxl/acpi: Introduce cxl_decoder objects") > Reported-by: Ben Widawsky <ben.widawsky@intel.com> > Signed-off-by: Dan Williams <dan.j.williams@intel.com> Tested-by: Ben Widawsky <ben.widawsky@intel.com> Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index 0fc1441be014..c1681248f322 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -251,6 +251,7 @@ static void cxl_decoder_release(struct device *dev) ida_free(&port->decoder_ida, cxld->id); kfree(cxld); + put_device(&port->dev); } static const struct device_type cxl_decoder_endpoint_type = { @@ -1202,7 +1203,10 @@ static struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, if (rc < 0) goto err; + /* need parent to stick around to release the id */ + get_device(&port->dev); cxld->id = rc; + cxld->nr_targets = nr_targets; seqlock_init(&cxld->target_lock); dev = &cxld->dev;
KASAN + DEBUG_KOBJECT_RELEASE reports a potential use-after-free in cxl_decoder_release() where it goes to reference its parent, a cxl_port, to free its id back to port->decoder_ida. BUG: KASAN: use-after-free in to_cxl_port+0x18/0x90 [cxl_core] Read of size 8 at addr ffff888119270908 by task kworker/35:2/379 CPU: 35 PID: 379 Comm: kworker/35:2 Tainted: G OE 5.17.0-rc2+ #198 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Workqueue: events kobject_delayed_cleanup Call Trace: <TASK> dump_stack_lvl+0x59/0x73 print_address_description.constprop.0+0x1f/0x150 ? to_cxl_port+0x18/0x90 [cxl_core] kasan_report.cold+0x83/0xdf ? to_cxl_port+0x18/0x90 [cxl_core] to_cxl_port+0x18/0x90 [cxl_core] cxl_decoder_release+0x2a/0x60 [cxl_core] device_release+0x5f/0x100 kobject_cleanup+0x80/0x1c0 The device core only guarantees parent lifetime until all children are unregistered. If a child needs a parent to complete its ->release() callback that child needs to hold a reference to extend the lifetime of the parent. Fixes: 40ba17afdfab ("cxl/acpi: Introduce cxl_decoder objects") Reported-by: Ben Widawsky <ben.widawsky@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- drivers/cxl/core/port.c | 4 ++++ 1 file changed, 4 insertions(+)