ab5d9d1751
commit df45bf84e4f5a48f23d4b1a07d21d566e8b587b2 upstream. Since the block is freed with last chain being put, once we reach the end of iteration of list_for_each_entry_safe, the block may be already freed. I'm hitting this only by creating and deleting clsact: [ 202.171952] ================================================================== [ 202.180182] BUG: KASAN: use-after-free in tcf_block_put_ext+0x240/0x390 [ 202.187590] Read of size 8 at addr ffff880225539a80 by task tc/796 [ 202.194508] [ 202.196185] CPU: 0 PID: 796 Comm: tc Not tainted 4.15.0-rc2jiri+ #5 [ 202.203200] Hardware name: Mellanox Technologies Ltd. "MSN2100-CB2F"/"SA001017", BIOS 5.6.5 06/07/2016 [ 202.213613] Call Trace: [ 202.216369] dump_stack+0xda/0x169 [ 202.220192] ? dma_virt_map_sg+0x147/0x147 [ 202.224790] ? show_regs_print_info+0x54/0x54 [ 202.229691] ? tcf_chain_destroy+0x1dc/0x250 [ 202.234494] print_address_description+0x83/0x3d0 [ 202.239781] ? tcf_block_put_ext+0x240/0x390 [ 202.244575] kasan_report+0x1ba/0x460 [ 202.248707] ? tcf_block_put_ext+0x240/0x390 [ 202.253518] tcf_block_put_ext+0x240/0x390 [ 202.258117] ? tcf_chain_flush+0x290/0x290 [ 202.262708] ? qdisc_hash_del+0x82/0x1a0 [ 202.267111] ? qdisc_hash_add+0x50/0x50 [ 202.271411] ? __lock_is_held+0x5f/0x1a0 [ 202.275843] clsact_destroy+0x3d/0x80 [sch_ingress] [ 202.281323] qdisc_destroy+0xcb/0x240 [ 202.285445] qdisc_graft+0x216/0x7b0 [ 202.289497] tc_get_qdisc+0x260/0x560 Fix this by holding the block also by chain 0 and put chain 0 explicitly, out of the list_for_each_entry_safe loop at the very end of tcf_block_put_ext. Fixes: efbf78973978 ("net_sched: get rid of rcu_barrier() in tcf_block_put_ext()") Signed-off-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net> Cc: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.