diff options
| author | Jiri Pirko <jiri@mellanox.com> | 2017-12-08 19:27:27 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-12-08 14:09:08 -0500 |
| commit | df45bf84e4f5a48f23d4b1a07d21d566e8b587b2 (patch) | |
| tree | 8b57781b4bad623260860182e031da18d5257acc /net/sched | |
| parent | fc8b81a5981f8220c79a86a213ed9a2aec327623 (diff) | |
net: sched: fix use-after-free in tcf_block_put_ext
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>
Diffstat (limited to 'net/sched')
| -rw-r--r-- | net/sched/cls_api.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index d51051dd8f7d..5b9b8a61e8c4 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -342,23 +342,24 @@ void tcf_block_put_ext(struct tcf_block *block, struct Qdisc *q, { struct tcf_chain *chain, *tmp; - /* Hold a refcnt for all chains, except 0, so that they don't disappear + /* Hold a refcnt for all chains, so that they don't disappear * while we are iterating. */ list_for_each_entry(chain, &block->chain_list, list) - if (chain->index) - tcf_chain_hold(chain); + tcf_chain_hold(chain); list_for_each_entry(chain, &block->chain_list, list) tcf_chain_flush(chain); tcf_block_offload_unbind(block, q, ei); - /* At this point, all the chains should have refcnt >= 1. Block will be - * freed after all chains are gone. - */ + /* At this point, all the chains should have refcnt >= 1. */ list_for_each_entry_safe(chain, tmp, &block->chain_list, list) tcf_chain_put(chain); + + /* Finally, put chain 0 and allow block to be freed. */ + chain = list_first_entry(&block->chain_list, struct tcf_chain, list); + tcf_chain_put(chain); } EXPORT_SYMBOL(tcf_block_put_ext); |