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The goto_chain termination action takes a reference of a chain. In that case, there is an issue when block_put is called tcf_chain_destroy directly. The follo-up call of tcf_chain_put by goto_chain action free works with memory that is already freed. This was caught by kasan: [ 220.337908] BUG: KASAN: use-after-free in tcf_chain_put+0x1b/0x50 [ 220.344103] Read of size 4 at addr ffff88036d1f2cec by task systemd-journal/261 [ 220.353047] CPU: 0 PID: 261 Comm: systemd-journal Not tainted 4.13.0-rc5jiri+ #54 [ 220.360661] Hardware name: Mellanox Technologies Ltd. Mellanox switch/Mellanox x86 mezzanine board, BIOS 4.6.5 08/02/2016 [ 220.371784] Call Trace: [ 220.374290] <IRQ> [ 220.376355] dump_stack+0xd5/0x150 [ 220.391485] print_address_description+0x86/0x410 [ 220.396308] kasan_report+0x181/0x4c0 [ 220.415211] tcf_chain_put+0x1b/0x50 [ 220.418949] free_tcf+0x95/0xc0 So allow tcf_chain_destroy to be called multiple times, free only in case the reference count drops to 0. Fixes: 5bc1701881e3 ("net: sched: introduce multichain support for filters") Signed-off-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.