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From: Tiwei Bie <tiwei.bie@linux.dev>
To: richard@nod.at, anton.ivanov@cambridgegreys.com,
	johannes@sipsolutions.net
Cc: linux-um@lists.infradead.org, tiwei.btw@antgroup.com,
	tiwei.bie@linux.dev
Subject: [PATCH] um: Fix FD copy size in os_rcv_fd_msg()
Date: Mon,  1 Sep 2025 08:27:15 +0800	[thread overview]
Message-ID: <20250901002715.3590541-1-tiwei.bie@linux.dev> (raw)

From: Tiwei Bie <tiwei.btw@antgroup.com>

When copying FDs, the copy size should not include the control
message header (cmsghdr). Fix it.

Fixes: 5cde6096a4dd ("um: generalize os_rcv_fd")
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/um/os-Linux/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c
index 617886d1fb1e..21f0e50fb1df 100644
--- a/arch/um/os-Linux/file.c
+++ b/arch/um/os-Linux/file.c
@@ -535,7 +535,7 @@ ssize_t os_rcv_fd_msg(int fd, int *fds, unsigned int n_fds,
 	    cmsg->cmsg_type != SCM_RIGHTS)
 		return n;
 
-	memcpy(fds, CMSG_DATA(cmsg), cmsg->cmsg_len);
+	memcpy(fds, CMSG_DATA(cmsg), cmsg->cmsg_len - CMSG_LEN(0));
 	return n;
 }
 
-- 
2.34.1



                 reply	other threads:[~2025-09-01  0:28 UTC|newest]

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