[PATCH] mtd: capture device name setting failure when adding mtd

[Edward Adam Davis]

syzbot reported a WARNING in release_mtd_partition. [1]

The reproducer uses "/proc/thread-self/fail-nth" to trigger the failure
of memory allocation when executing dev_set_name() in add_mtd_device(),
which eventually causes device_register() to fail because the device name
is not set, and finally triggers a warning in put_device().

[1]
WARNING: CPU: 0 PID: 5826 at drivers/mtd/mtdpart.c:37 release_mtd_partition+0x71/0x90 drivers/mtd/mtdpart.c:37
Modules linked in:
CPU: 0 UID: 0 PID: 5826 Comm: syz-executor397 Not tainted 6.13.0-syzkaller-09734-g2a9f04bde07a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
RIP: 0010:release_mtd_partition+0x71/0x90 drivers/mtd/mtdpart.c:37
Code: 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 1e 48 8b 7b 38 e8 ef 84 cd fb 48 89 df 5b 5d e9 e5 84 cd fb e8 70 4a 75 fb 90 <0f> 0b 90 eb c2 e8 a5 29 d8 fb eb db 48 89 ef e8 9b 29 d8 fb eb a5
RSP: 0018:ffffc90003e1f828 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88802c1d1000 RCX: ffffffff8b417995
RDX: ffff8880310c3c00 RSI: ffffffff86439150 RDI: ffff88802c1d1000
RBP: ffff88802c1d1648 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000004 R11: ffffffff81000130 R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  000055558b9cd480(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 0000000034aca000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 mtd_release+0xa0/0xd0 drivers/mtd/mtdcore.c:101
 device_release+0xa1/0x240 drivers/base/core.c:2567
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1e4/0x5a0 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3773
 add_mtd_device+0xbb3/0x1700 drivers/mtd/mtdcore.c:750
 mtd_add_partition+0x300/0x650 drivers/mtd/mtdpart.c:279
 mtdchar_blkpg_ioctl+0x20d/0x250 drivers/mtd/mtdchar.c:562
 mtdchar_ioctl+0xbbe/0x2050 drivers/mtd/mtdchar.c:1216
 mtdchar_unlocked_ioctl+0xb0/0xf0 drivers/mtd/mtdchar.c:1239
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported-by: syzbot+074732af3fc6c528f8a0@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=074732af3fc6c528f8a0
Tested-by: syzbot+074732af3fc6c528f8a0@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
---
 drivers/mtd/mtdcore.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 724f917f91ba..a71cd75858e4 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -741,7 +741,8 @@ int add_mtd_device(struct mtd_info *mtd)
 	mtd->dev.type = &mtd_devtype;
 	mtd->dev.class = &mtd_class;
 	mtd->dev.devt = MTD_DEVT(i);
-	dev_set_name(&mtd->dev, "mtd%d", i);
+	if (error = dev_set_name(&mtd->dev, "mtd%d", i))
+		goto fail_devname;
 	dev_set_drvdata(&mtd->dev, mtd);
 	mtd_check_of_node(mtd);
 	of_node_get(mtd_get_of_node(mtd));
@@ -790,6 +791,7 @@ int add_mtd_device(struct mtd_info *mtd)
 	device_unregister(&mtd->dev);
 fail_added:
 	of_node_put(mtd_get_of_node(mtd));
+fail_devname:
 	idr_remove(&mtd_idr, i);
 fail_locked:
 	mutex_unlock(&mtd_table_mutex);
-- 
2.43.0