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ksmbd: skip lock-range check on equal size to avoid size==0 underflow

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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.

Cc: stable@vger.kernel.org
Reported-by: Qianchang Zhao <pioooooooooip@gmail.com>
Reported-by: Zhitong Liu <liuzhitong1993@gmail.com>
Signed-off-by: Qianchang Zhao <pioooooooooip@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Qianchang Zhao 2025-11-09 10:00:55 +09:00 committed by Steve French
parent 9c98f5eec8
commit 5d510ac316
1 changed files with 4 additions and 1 deletions
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5
fs/smb/server/vfs.c
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@ -324,6 +324,9 @@ static int check_lock_range(struct file *filp, loff_t start, loff_t end,
struct file_lock_context *ctx = locks_inode_context(file_inode(filp));
int error = 0;
if (start == end)
return 0;
if (!ctx || list_empty_careful(&ctx->flc_posix))
return 0;
@ -828,7 +831,7 @@ 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);
}