From: Lukasz Bartosik lb@semihalf.com
[ Upstream commit 8d3c0c01cb2e36b2bf3c06a82b18b228d0c8f5d0 ]
Fix invalid usage of a list_for_each_entry cursor in clk_notifier_register(). When list is empty or if the list is completely traversed (without breaking from the loop on one of the entries) then the list cursor does not point to a valid entry and therefore should not be used.
The issue was dicovered when running 5.12-rc1 kernel on x86_64 with KASAN enabled: BUG: KASAN: global-out-of-bounds in clk_notifier_register+0xab/0x230 Read of size 8 at addr ffffffffa0d10588 by task swapper/0/1
CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.12.0-rc1 #1 Hardware name: Google Caroline/Caroline, BIOS Google_Caroline.7820.430.0 07/20/2018 Call Trace: dump_stack+0xee/0x15c print_address_description+0x1e/0x2dc kasan_report+0x188/0x1ce ? clk_notifier_register+0xab/0x230 ? clk_prepare_lock+0x15/0x7b ? clk_notifier_register+0xab/0x230 clk_notifier_register+0xab/0x230 dw8250_probe+0xc01/0x10d4 ... Memory state around the buggy address: ffffffffa0d10480: 00 00 00 00 00 03 f9 f9 f9 f9 f9 f9 00 00 00 00 ffffffffa0d10500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f9 f9
ffffffffa0d10580: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 00 00
^ ffffffffa0d10600: 00 00 00 00 00 00 f9 f9 f9 f9 f9 f9 00 00 00 00 ffffffffa0d10680: 00 00 00 00 00 00 00 00 f9 f9 f9 f9 00 00 00 00 ==================================================================
Fixes: b2476490ef11 ("clk: introduce the common clock framework") Reported-by: Lukasz Majczak lma@semihalf.com Signed-off-by: Lukasz Bartosik lb@semihalf.com Link: https://lore.kernel.org/r/20210401225149.18826-1-lb@semihalf.com Signed-off-by: Stephen Boyd sboyd@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/clk/clk.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index f83dac54ed85..dae090124263 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -4262,20 +4262,19 @@ int clk_notifier_register(struct clk *clk, struct notifier_block *nb) /* search the list of notifiers for this clk */ list_for_each_entry(cn, &clk_notifier_list, node) if (cn->clk == clk) - break; + goto found;
/* if clk wasn't in the notifier list, allocate new clk_notifier */ - if (cn->clk != clk) { - cn = kzalloc(sizeof(*cn), GFP_KERNEL); - if (!cn) - goto out; + cn = kzalloc(sizeof(*cn), GFP_KERNEL); + if (!cn) + goto out;
- cn->clk = clk; - srcu_init_notifier_head(&cn->notifier_head); + cn->clk = clk; + srcu_init_notifier_head(&cn->notifier_head);
- list_add(&cn->node, &clk_notifier_list); - } + list_add(&cn->node, &clk_notifier_list);
+found: ret = srcu_notifier_chain_register(&cn->notifier_head, nb);
clk->core->notifier_count++;