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new 3cbd3bf92c7 net/local: Give the whole address of a datagram sender.
3cbd3bf92c7 is described below
commit 3cbd3bf92c78041794a9d0ba493fd48ce570f7d4
Author: Marco Casaroli <[email protected]>
AuthorDate: Fri Nov 6 11:30:49 2026 +0100
net/local: Give the whole address of a datagram sender.
recvmsg() of a local datagram socket set msg_namelen to the length of the
name
without the family, so it was two bytes short. A kernel build copies only
that length back to the program, so the program lost the last two bytes of
the
name: a server could not answer the client. Also, the name and its NUL
could
go two bytes past the buffer of the caller, because the limit did not count
the family.
Count the family and the NUL in both places. The address of an unbound
sender has the family only. The behavior is the same in the flat, protected
and kernel builds, apart from the two bytes that a kernel build lost.
Assisted-by: Claude Code:claude-opus-5-5
Signed-off-by: Marco Casaroli <[email protected]>
---
net/local/local_recvmsg.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/net/local/local_recvmsg.c b/net/local/local_recvmsg.c
index c8c51f6a7c7..686270fc10e 100644
--- a/net/local/local_recvmsg.c
+++ b/net/local/local_recvmsg.c
@@ -560,9 +560,13 @@ psock_dgram_recvfrom(FAR struct socket *psock, FAR void
*buf, size_t len,
readlen = addrlen;
offset += sizeof(pktlen);
- if (from && fromlen && *fromlen)
+ /* The address has the family, the name and a NUL. The address of an
+ * unbound sender has the family only.
+ */
+
+ if (from && fromlen && *fromlen > sizeof(sa_family_t))
{
- pathlen = MIN(*fromlen - 1, readlen);
+ pathlen = MIN(*fromlen - sizeof(sa_family_t) - 1, readlen);
ret = psock_fifo_read(psock, from->sa_data, offset,
&pathlen, flags, false);
if (ret < 0)
@@ -573,7 +577,12 @@ psock_dgram_recvfrom(FAR struct socket *psock, FAR void
*buf, size_t len,
from->sa_family = AF_LOCAL;
from->sa_data[pathlen] = '\0';
- *fromlen = pathlen;
+ *fromlen = sizeof(sa_family_t);
+ if (addrlen > 0)
+ {
+ *fromlen += pathlen + 1;
+ }
+
readlen -= pathlen;
}
