82e85c0e7f
commit 8e24edddad152b998b37a7f583175137ed2e04a5 upstream. nested target/match_revfn() calls work with xt[NFPROTO_UNSPEC] lists without taking xt[NFPROTO_UNSPEC].mutex. This can race with module unload and cause host to crash: general protection fault: 0000 [#1] Modules linked in: ... [last unloaded: xt_cluster] CPU: 0 PID: 542455 Comm: iptables RIP: 0010:[<ffffffff8ffbd518>] [<ffffffff8ffbd518>] strcmp+0x18/0x40 RDX: 0000000000000003 RSI: ffff9a5a5d9abe10 RDI: dead000000000111 R13: ffff9a5a5d9abe10 R14: ffff9a5a5d9abd8c R15: dead000000000100 (VvS: %R15 -- &xt_match, %RDI -- &xt_match.name, xt_cluster unregister match in xt[NFPROTO_UNSPEC].match list) Call Trace: [<ffffffff902ccf44>] match_revfn+0x54/0xc0 [<ffffffff902ccf9f>] match_revfn+0xaf/0xc0 [<ffffffff902cd01e>] xt_find_revision+0x6e/0xf0 [<ffffffffc05a5be0>] do_ipt_get_ctl+0x100/0x420 [ip_tables] [<ffffffff902cc6bf>] nf_getsockopt+0x4f/0x70 [<ffffffff902dd99e>] ip_getsockopt+0xde/0x100 [<ffffffff903039b5>] raw_getsockopt+0x25/0x50 [<ffffffff9026c5da>] sock_common_getsockopt+0x1a/0x20 [<ffffffff9026b89d>] SyS_getsockopt+0x7d/0xf0 [<ffffffff903cbf92>] system_call_fastpath+0x25/0x2a Fixes: 656caff20e1 ("netfilter 04/09: x_tables: fix match/target revision lookup") Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Reviewed-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.