Re: [PATCH] net: bridge: fix potential null pointer dereference on return from br_port_get_rtnl()

On 06/22/2018 01:20 AM, David Miller wrote:

From: Garry McNulty <redacted>
Date: Thu, 21 Jun 2018 21:14:27 +0100

quoted

br_port_get_rtnl() can return NULL if the network device is not a bridge
port (IFF_BRIDGE_PORT flag not set). br_port_slave_changelink() and
br_port_fill_slave_info() callbacks dereference this pointer without
checking. Currently this is not a problem because slave devices always
set this flag. Add null check in case these conditions ever changye.

Detected by CoverityScan, CID 1339613 ("Dereference null return value")

Signed-off-by: Garry McNulty <redacted>

I don't think this is reasonable.

The bridge code will never, ever, install a slave that doesn't have
that bit set.  It's the most fundamental aspect of how these objects
are managed.

+1

This keeps coming up, here's the previous one:
https://patchwork.ozlabs.org/patch/896046/

Please do a more thorough check if these conditions can actually occur.
In this case, as Dave said, they cannot.

To be explicit as with the patch I mentioned above:
Nacked-by: Nikolay Aleksandrov [off-list ref]

You can find more info in my reply to the patch above.

Thanks,
 Nik