6.17-stable review patch. If anyone has any objections, please let me know.
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From: Stanislav Fomichev sdf@fomichev.me
[ Upstream commit 18282100d7040614b553f1cad737cb689c04e2b9 ]
tcp_recvmsg_dmabuf can export the following errors: - EFAULT when linear copy fails - ETOOSMALL when cmsg put fails - ENODEV if one of the frags is readable - ENOMEM on xarray failures
But they are all ignored and replaced by EFAULT in the caller (tcp_recvmsg_locked). Expose real error to the userspace to add more transparency on what specifically fails.
In non-devmem case (skb_copy_datagram_msg) doing `if (!copied) copied=-EFAULT` is ok because skb_copy_datagram_msg can return only EFAULT.
Reviewed-by: David Ahern dsahern@kernel.org Reviewed-by: Mina Almasry almasrymina@google.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: Stanislav Fomichev sdf@fomichev.me Link: https://patch.msgid.link/20250910162429.4127997-1-sdf@fomichev.me Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/tcp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index ba36f558f144c..f421cad69d8c9 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2821,9 +2821,9 @@ static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len,
err = tcp_recvmsg_dmabuf(sk, skb, offset, msg, used); - if (err <= 0) { + if (err < 0) { if (!copied) - copied = -EFAULT; + copied = err;
break; }