From 0326649a1a37a45d025cf93b8eaa43052d19e615 Mon Sep 17 00:00:00 2001 From: Yang Yingliang Date: Mon, 11 Oct 2021 16:03:02 +0800 Subject: [PATCH] rtc: class: return error code when cdev_device_add() failed I got a null-ptr-deref report when doing fault injection test: general protection fault, probably for non-canonical address 0xdffffc0000000022: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000110-0x0000000000000117] CPU: 1 PID: 1028 Comm: 33 Not tainted 5.15.0-rc3-00111-gf5dad42ed4fe-dirty #481 2a70b3e6ca240b8638beac7ef491cce6183bbec7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 RIP: 0010:device_del+0x132/0xdc0 Code: 48 c1 ea 03 80 3c 02 00 0f 85 4f 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 7b 48 4d 8d a7 10 01 00 00 4c 89 e2 48 c1 ea 03 <0f> b6 04 02 84 c0 74 06 0f 8e 7f 0a 00 00 45 0f b6 b7 10 01 00 00 RSP: 0018:ffffc90002e876b8 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: ffff88801eb84000 RCX: ffffffff97227644 RDX: 0000000000000022 RSI: ffff8880146a0000 RDI: 0000000000000002 RBP: ffff88801eb84120 R08: fffffbfff349a60d R09: fffffbfff349a60d R10: ffffc90002e876b8 R11: fffffbfff349a60c R12: 0000000000000110 R13: 0000000000000001 R14: ffffc90002e87848 R15: 0000000000000000 FS: 00007fa514973500(0000) GS:ffff888104600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa51474ccb0 CR3: 000000002bcb0001 CR4: 0000000000770ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: ? write_comp_data+0x2a/0x90 ? cleanup_glue_dir+0x260/0x260 ? is_rtc_hctosys.isra.0+0xb9/0xf0 ? rtc_proc_show+0x440/0x440 ? rcu_read_lock_held_common+0xe/0xa0 ? rcu_read_lock_sched_held+0x62/0xe0 cdev_device_del+0x1a/0x80 devm_rtc_unregister_device+0x37/0x80 release_nodes+0xc3/0x3b0 If cdev_device_add() fails, 'dev->p' is not set, it causes null-ptr-deref when calling cdev_device_del(), return error code when cdev_device_add() failed to fix this. Reported-by: Hulk Robot Fixes: 3068a254d5519 ("rtc: introduce new registration method") Signed-off-by: Yang Yingliang --- drivers/rtc/class.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c index 1f18c39a4b8295..76422faee05ba1 100644 --- a/drivers/rtc/class.c +++ b/drivers/rtc/class.c @@ -399,12 +399,14 @@ int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc) rtc_dev_prepare(rtc); err = cdev_device_add(&rtc->char_dev, &rtc->dev); - if (err) + if (err) { dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n", MAJOR(rtc->dev.devt), rtc->id); - else + return err; + } else { dev_dbg(rtc->dev.parent, "char device (%d:%d)\n", MAJOR(rtc->dev.devt), rtc->id); + } rtc_proc_add_device(rtc);