From: Qianchang Zhao <pioooooooooip@gmail.com>
To: Namjae Jeon <linkinjeon@kernel.org>, Steve French <smfrench@gmail.com>
Cc: gregkh@linuxfoundation.org, linux-cifs@vger.kernel.org,
linux-kernel@vger.kernel.org, security@kernel.org,
Zhitong Liu <liuzhitong1993@gmail.com>,
Qianchang Zhao <pioooooooooip@gmail.com>,
stable@vger.kernel.org
Subject: [PATCH v2] ksmbd: vfs: skip lock-range check on equal size to avoid size==0 underflow
Date: Sun, 9 Nov 2025 00:57:12 +0900 [thread overview]
Message-ID: <20251108155712.384021-1-pioooooooooip@gmail.com> (raw)
In-Reply-To: <CAKYAXd-R8NGDzQ-GTM67QbCxwJTCMGNhxKBo1a0sm0XBDqftLw@mail.gmail.com>
When size equals the current i_size (including 0), the code used to call
check_lock_range(filp, i_size, size - 1, WRITE), which computes `size - 1`
and can underflow for size==0. Skip the equal case.
Reported-by: Qianchang Zhao <pioooooooooip@gmail.com>
Reported-by: Zhitong Liu <liuzhitong1993@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Qianchang Zhao <pioooooooooip@gmail.com>
---
fs/smb/server/vfs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
index 891ed2dc2..d068b78a3 100644
--- a/fs/smb/server/vfs.c
+++ b/fs/smb/server/vfs.c
@@ -828,7 +828,7 @@ int ksmbd_vfs_truncate(struct ksmbd_work *work,
if (size < inode->i_size) {
err = check_lock_range(filp, size,
inode->i_size - 1, WRITE);
- } else {
+ } else if (size > inode->i_size) {
err = check_lock_range(filp, inode->i_size,
size - 1, WRITE);
}
--
2.34.1
next prev parent reply other threads:[~2025-11-08 15:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <2025110803-retrace-unnatural-127f@gregkh>
2025-11-08 12:36 ` [PATCH] ksmbd: vfs: fix truncate lock-range check for shrink/grow and avoid size==0 underflow Qianchang Zhao
2025-11-08 14:46 ` Namjae Jeon
2025-11-08 15:57 ` Qianchang Zhao [this message]
2025-11-09 1:32 ` [PATCH v2] ksmbd: vfs: skip lock-range check on equal size to " Namjae Jeon
2025-11-08 16:00 ` [PATCH] ksmbd: vfs: fix truncate lock-range check for shrink/grow and " くさあさ
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