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clk: fix invalid usage of list cursor in register

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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: b2476490ef ("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>
This commit is contained in:
Lukasz Bartosik 2021-04-02 00:51:48 +02:00 committed by Stephen Boyd
parent e5c359f70e
commit 8d3c0c01cb
1 changed files with 8 additions and 9 deletions
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17
drivers/clk/clk.c
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@ -4357,20 +4357,19 @@ 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++;