This is a note to let you know that I've just added the patch titled
netlink: Don't reorder loads/stores before marking mmap netlink frame as available
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netlink-don-t-reorder-loads-stores-before-marking-mmap-netlink-frame-as-available.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Sat Jan 17 18:13:47 PST 2015
From: Thomas Graf <tgraf@xxxxxxx>
Date: Thu, 18 Dec 2014 10:30:26 +0000
Subject: netlink: Don't reorder loads/stores before marking mmap netlink frame as available
From: Thomas Graf <tgraf@xxxxxxx>
[ Upstream commit a18e6a186f53af06937a2c268c72443336f4ab56 ]
Each mmap Netlink frame contains a status field which indicates
whether the frame is unused, reserved, contains data or needs to
be skipped. Both loads and stores may not be reordeded and must
complete before the status field is changed and another CPU might
pick up the frame for use. Use an smp_mb() to cover needs of both
types of callers to netlink_set_status(), callers which have been
reading data frame from the frame, and callers which have been
filling or releasing and thus writing to the frame.
- Example code path requiring a smp_rmb():
memcpy(skb->data, (void *)hdr + NL_MMAP_HDRLEN, hdr->nm_len);
netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);
- Example code path requiring a smp_wmb():
hdr->nm_uid = from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);
hdr->nm_gid = from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);
netlink_frame_flush_dcache(hdr);
netlink_set_status(hdr, NL_MMAP_STATUS_VALID);
Fixes: f9c228 ("netlink: implement memory mapped recvmsg()")
Reported-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: Thomas Graf <tgraf@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/netlink/af_netlink.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -399,9 +399,9 @@ static enum nl_mmap_status netlink_get_s
static void netlink_set_status(struct nl_mmap_hdr *hdr,
enum nl_mmap_status status)
{
+ smp_mb();
hdr->nm_status = status;
flush_dcache_page(pgvec_to_page(hdr));
- smp_wmb();
}
static struct nl_mmap_hdr *
Patches currently in stable-queue which might be from tgraf@xxxxxxx are
queue-3.10/netlink-always-copy-on-mmap-tx.patch
queue-3.10/netlink-don-t-reorder-loads-stores-before-marking-mmap-netlink-frame-as-available.patch
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