diff options
| author | Xion Wang <xion.wang@mediatek.com> | 2025-09-04 14:37:04 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-09-06 19:43:18 +0200 |
| commit | e28022873c0d051e980c4145f1965cab5504b498 (patch) | |
| tree | 3bb363a27d035c9b07553dc167317fea8817bf35 | |
| parent | ceda408c0d1d41094ad125332c6fb1d488e61c0c (diff) | |
char: Use list_del_init() in misc_deregister() to reinitialize list pointer
Currently, misc_deregister() uses list_del() to remove the device
from the list. After list_del(), the list pointers are set to
LIST_POISON1 and LIST_POISON2, which may help catch use-after-free bugs,
but does not reset the list head.
If misc_deregister() is called more than once on the same device,
list_empty() will not return true, and list_del() may be called again,
leading to undefined behavior.
Replace list_del() with list_del_init() to reinitialize the list head
after deletion. This makes the code more robust against double
deregistration and allows safe usage of list_empty() on the miscdevice
after deregistration.
[ Note, this seems to keep broken out-of-tree drivers from doing foolish
things. While this does not matter for any in-kernel drivers,
external drivers could use a bit of help to show them they shouldn't
be doing stuff like re-registering misc devices - gregkh ]
Signed-off-by: Xion Wang <xion.wang@mediatek.com>
Link: https://lore.kernel.org/r/20250904063714.28925-2-xion.wang@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/char/misc.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/char/misc.c b/drivers/char/misc.c index 69e8ce02e099..726516fb0a3b 100644 --- a/drivers/char/misc.c +++ b/drivers/char/misc.c @@ -284,7 +284,7 @@ EXPORT_SYMBOL(misc_register); void misc_deregister(struct miscdevice *misc) { mutex_lock(&misc_mtx); - list_del(&misc->list); + list_del_init(&misc->list); device_destroy(&misc_class, MKDEV(MISC_MAJOR, misc->minor)); misc_minor_free(misc->minor); if (misc->minor > MISC_DYNAMIC_MINOR) |