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authorDan Williams <dan.j.williams@intel.com>2022-02-17 03:25:11 +0300
committerDan Williams <dan.j.williams@intel.com>2022-02-18 03:51:13 +0300
commit74be98774dfbc5b8b795db726bd772e735d2edd4 (patch)
tree4e2dd92b77d4c312cce779a7e4a6c19783c4cc25 /drivers/cxl
parent41ae9105f5e23e98a1734be2eeddddf488e42c2e (diff)
downloadlinux-74be98774dfbc5b8b795db726bd772e735d2edd4.tar.xz
cxl/port: Hold port reference until decoder release
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> Tested-by: Ben Widawsky <ben.widawsky@intel.com> Reviewed-by: Ben Widawsky <ben.widawsky@intel.com> Link: https://lore.kernel.org/r/164505751190.4175768.13324905271463416712.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/cxl')
-rw-r--r--drivers/cxl/core/port.c4
1 files changed, 4 insertions, 0 deletions
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;