| Message ID | CAH2r5mvf3zjMb3=ceL9wknZhMwp6CrOQEyzZ7HaXDNidYpLCBQ@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [SMB3,client] Server interface count incorrectly calculated | expand |
On 10/15/2022 6:10 PM, Steve French wrote: > smb3: interface count displayed incorrectly > > The "Server interfaces" count in /proc/fs/cifs/DebugData increases > as the interfaces are requeried, rather than being reset to the new > value. This could cause a problem if the server disabled > multichannel as the iface_count is checked in try_adding_channels > to see if multichannel still supported. > > Cc: <stable@vger.kernel.org> > > See attached > This zeroes the ses->iface_count under the lock, but the whole routine is dropping and re-taking the same lock many times, and finally sets the iface_count without holding the lock at all. Isn't this whole sequence broken? Tom.
On 10/17/2022 5:26 PM, Steve French wrote: > > > On Mon, Oct 17, 2022, 16:03 Tom Talpey <tom@talpey.com > <mailto:tom@talpey.com>> wrote: > > On 10/15/2022 6:10 PM, Steve French wrote: > > smb3: interface count displayed incorrectly > > > > The "Server interfaces" count in /proc/fs/cifs/DebugData increases > > as the interfaces are requeried, rather than being reset to the new > > value. This could cause a problem if the server disabled > > multichannel as the iface_count is checked in try_adding_channels > > to see if multichannel still supported. > > > > Cc: <stable@vger.kernel.org <mailto:stable@vger.kernel.org>> > > > > See attached > > > > This zeroes the ses->iface_count under the lock, but the whole > routine is dropping and re-taking the same lock many times, > and finally sets the iface_count without holding the lock at > all. > > > I updated the patch earlier today to fix that existing issue as well > (served into same patch). If I missed something let me know I was just looking at the patch attached to the message I replied to. I'll look again, but it will have to be tomorrow. Tom.
On Tue, Oct 18, 2022 at 3:22 AM Steve French <smfrench@gmail.com> wrote: > > Updated one is also at > > https://git.samba.org/?p=sfrench/cifs-2.6.git;a=patch;h=3f825b8fa93bb300e60c932753e8c5274b253a77 > > On Mon, Oct 17, 2022, 16:28 Tom Talpey <tom@talpey.com> wrote: >> >> On 10/17/2022 5:26 PM, Steve French wrote: >> > >> > >> > On Mon, Oct 17, 2022, 16:03 Tom Talpey <tom@talpey.com >> > <mailto:tom@talpey.com>> wrote: >> > >> > On 10/15/2022 6:10 PM, Steve French wrote: >> > > smb3: interface count displayed incorrectly >> > > >> > > The "Server interfaces" count in /proc/fs/cifs/DebugData increases >> > > as the interfaces are requeried, rather than being reset to the new >> > > value. This could cause a problem if the server disabled >> > > multichannel as the iface_count is checked in try_adding_channels >> > > to see if multichannel still supported. >> > > >> > > Cc: <stable@vger.kernel.org <mailto:stable@vger.kernel.org>> >> > > >> > > See attached >> > > >> > >> > This zeroes the ses->iface_count under the lock, but the whole >> > routine is dropping and re-taking the same lock many times, >> > and finally sets the iface_count without holding the lock at >> > all. >> > >> > >> > I updated the patch earlier today to fix that existing issue as well >> > (served into same patch). If I missed something let me know >> >> I was just looking at the patch attached to the message I replied to. >> I'll look again, but it will have to be tomorrow. >> >> Tom. Looks good to me for fixing the issue. One or two more changes needed in this area. You can expect additional patches from me in the coming days.
From 1d2aef099583e39610580d20fb86f6f99b64c782 Mon Sep 17 00:00:00 2001 From: Steve French <stfrench@microsoft.com> Date: Sat, 15 Oct 2022 17:02:30 -0500 Subject: [PATCH] smb3: interface count displayed incorrectly The "Server interfaces" count in /proc/fs/cifs/DebugData increases as the interfaces are requeried, rather than being reset to the new value. This could cause a problem if the server disabled multichannel as the iface_count is checked in try_adding_channels to see if multichannel still supported. Cc: <stable@vger.kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com> --- fs/cifs/smb2ops.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 17b25153cb68..7ee1dd635faf 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -530,6 +530,7 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf, p = buf; spin_lock(&ses->iface_lock); + ses->iface_count = 0; /* * Go through iface_list and do kref_put to remove * any unused ifaces. ifaces in use will be removed -- 2.34.1