| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.14 53/87] netlink: Fix handling of error from netlink_dump(). | Date | Sat, 26 Jul 2014 12:02:27 -0700 |
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3.14-stable review patch. If anyone has any objections, please let me know.
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From: Ben Pfaff <blp@nicira.com>
[ Upstream commit ac30ef832e6af0505b6f0251a6659adcfa74975e ]
netlink_dump() returns a negative errno value on error. Until now, netlink_recvmsg() directly recorded that negative value in sk->sk_err, but that's wrong since sk_err takes positive errno values. (This manifests as userspace receiving a positive return value from the recv() system call, falsely indicating success.) This bug was introduced in the commit that started checking the netlink_dump() return value, commit b44d211 (netlink: handle errors from netlink_dump()).
Multithreaded Netlink dumps are one way to trigger this behavior in practice, as described in the commit message for the userspace workaround posted here: http://openvswitch.org/pipermail/dev/2014-June/042339.html
This commit also fixes the same bug in netlink_poll(), introduced in commit cd1df525d (netlink: add flow control for memory mapped I/O).
Signed-off-by: Ben Pfaff <blp@nicira.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/netlink/af_netlink.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -636,7 +636,7 @@ static unsigned int netlink_poll(struct while (nlk->cb_running && netlink_dump_space(nlk)) { err = netlink_dump(sk); if (err < 0) { - sk->sk_err = err; + sk->sk_err = -err; sk->sk_error_report(sk); break; } @@ -2448,7 +2448,7 @@ static int netlink_recvmsg(struct kiocb atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) { ret = netlink_dump(sk); if (ret) { - sk->sk_err = ret; + sk->sk_err = -ret; sk->sk_error_report(sk); } }
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