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Florian Westphal
e58a171d35
We are not allowed to return an error at this point.
Looking at the code it looks like ret is always 0 at this
point, but its not.
t = find_table_lock(net, repl->name, &ret, &ebt_mutex);
... this can return a valid table, with ret != 0.
This bug causes update of table->private with the new
blob, but then frees the blob right away in the caller.
Syzbot report:
BUG: KASAN: vmalloc-out-of-bounds in __ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168
Read of size 4 at addr ffffc90005425000 by task kworker/u4:4/74
Workqueue: netns cleanup_net
Call Trace:
kasan_report+0xbf/0x1f0 mm/kasan/report.c:517
__ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168
ebt_unregister_table+0x35/0x40 net/bridge/netfilter/ebtables.c:1372
ops_exit_list+0xb0/0x170 net/core/net_namespace.c:169
cleanup_net+0x4ee/0xb10 net/core/net_namespace.c:613
...
ip(6)tables appears to be ok (ret should be 0 at this point) but make
this more obvious.
Fixes: c58dd2dd44 ("netfilter: Can't fail and free after table replacement")
Reported-by: syzbot+f61594de72d6705aea03@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.