[PATCH 6.1 250/609] libceph: bound get_version reply decode to front len

6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Douya Le <[email protected]>

commit d3c32939fa0e3ee9b883b9a0fd1972c5c444e3d0 upstream.

handle_get_version_reply() uses msg->front_alloc_len as the decode
boundary for MON_GET_VERSION_REPLY.  That is the size of the reused
reply buffer, not the number of bytes actually received.

A truncated reply can therefore pass ceph_decode_need() and decode the
second u64 from stale tail bytes left in the buffer by an earlier
message, causing an uninitialized memory read.

Use msg->front.iov_len as the receive-side decode boundary, matching
other libceph reply handlers and limiting decoding to the bytes that
were actually read from the wire.

Cc: [email protected]
Fixes: 513a8243d67f ("libceph: mon_get_version request infrastructure")
Reported-by: Yuan Tan <[email protected]>
Reported-by: Zhengchuan Liang <[email protected]>
Reported-by: Xin Liu <[email protected]>
Assisted-by: Codex:GPT-5.4
Signed-off-by: Douya Le <[email protected]>
Signed-off-by: Ren Wei <[email protected]>
Reviewed-by: Viacheslav Dubeyko <[email protected]>
Signed-off-by: Ilya Dryomov <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 net/ceph/mon_client.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -821,7 +821,7 @@ static void handle_get_version_reply(str
 	struct ceph_mon_generic_request *req;
 	u64 tid = le64_to_cpu(msg->hdr.tid);
 	void *p = msg->front.iov_base;
-	void *end = p + msg->front_alloc_len;
+	void *const end = p + msg->front.iov_len;
 	u64 handle;
 
 	dout("%s msg %p tid %llu\n", __func__, msg, tid);