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misc: nsm: do not unlock mutex before locking it

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nsm_dev_ioctl() jumps to the common out label when the initial
copy_from_user() fails. That failure path runs before
mutex_lock(&nsm->lock), but the out label unconditionally calls
mutex_unlock(&nsm->lock).

Return -EFAULT directly for the pre-lock copy_from_user() failure so
only paths that acquired the mutex release it.

Signed-off-by: Vu Nguyen Anh Khoa <khoavna.tin.2225@gmail.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260621085743.76329-2-khoavna.tin.2225@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vu Nguyen Anh Khoa
2026-06-21 15:57:43 +07:00
committed by Greg Kroah-Hartman
parent 6994c8b4ef
commit 937cd823bb
1 changed files with 1 additions and 2 deletions
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3
drivers/misc/nsm.c
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@@ -365,9 +365,8 @@ static long nsm_dev_ioctl(struct file *file, unsigned int cmd,
return -EINVAL;
/* Copy user argument struct to kernel argument struct */
r = -EFAULT;
if (copy_from_user(&raw, argp, _IOC_SIZE(cmd)))
goto out;
return -EFAULT;
mutex_lock(&nsm->lock);