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[ Upstream commitfd3e71a9f7] conn_free() holds lock with spin_lock() and it is called by both nf_conncount_lookup() and nf_conncount_gc_list(). nf_conncount_lookup() is called from bottom-half context and nf_conncount_gc_list() from process context. So that spin_lock() call is not safe. Hence conn_free() should use spin_lock_bh() instead of spin_lock(). test commands: %nft add table ip filter %nft add chain ip filter input { type filter hook input priority 0\; } %nft add rule filter input meter test { ip saddr ct count over 2 } \ counter splat looks like: [ 461.996507] ================================ [ 461.998999] WARNING: inconsistent lock state [ 461.998999] 4.19.0-rc6+ #22 Not tainted [ 461.998999] -------------------------------- [ 461.998999] inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. [ 461.998999] kworker/0:2/134 [HC0[0]:SC0[0]:HE1:SE1] takes: [ 461.998999] 00000000a71a559a (&(&list->list_lock)->rlock){+.?.}, at: conn_free+0x69/0x2b0 [nf_conncount] [ 461.998999] {IN-SOFTIRQ-W} state was registered at: [ 461.998999] _raw_spin_lock+0x30/0x70 [ 461.998999] nf_conncount_add+0x28a/0x520 [nf_conncount] [ 461.998999] nft_connlimit_eval+0x401/0x580 [nft_connlimit] [ 461.998999] nft_dynset_eval+0x32b/0x590 [nf_tables] [ 461.998999] nft_do_chain+0x497/0x1430 [nf_tables] [ 461.998999] nft_do_chain_ipv4+0x255/0x330 [nf_tables] [ 461.998999] nf_hook_slow+0xb1/0x160 [ ... ] [ 461.998999] other info that might help us debug this: [ 461.998999] Possible unsafe locking scenario: [ 461.998999] [ 461.998999] CPU0 [ 461.998999] ---- [ 461.998999] lock(&(&list->list_lock)->rlock); [ 461.998999] <Interrupt> [ 461.998999] lock(&(&list->list_lock)->rlock); [ 461.998999] [ 461.998999] *** DEADLOCK *** [ 461.998999] [ ... ] Fixes:5c789e131c("netfilter: nf_conncount: Add list lock and gc worker, and RCU for init tree search") Signed-off-by: Taehee Yoo <ap420073@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Sasha Levin <sashal@kernel.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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.