From: Quentin Schulz <foss+kernel@0leil.net>
To: Linus Walleij <linus.walleij@linaro.org>,
Bartosz Golaszewski <brgl@bgdev.pl>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: "Heiko Stuebner" <heiko.stuebner@cherry.de>,
stable@vger.kernel.org, linux-gpio@vger.kernel.org,
linux-kernel@vger.kernel.org,
"Bartosz Golaszewski" <bartosz.golaszewski@linaro.org>,
"Quentin Schulz" <quentin.schulz@cherry.de>,
"Paweł Narewski" <pawel.narewski@nokia.com>,
"Jakub Lewalski" <jakub.lewalski@nokia.com>,
"Bartosz Golaszewski" <bartosz.golaszewski@oss.qualcomm.com>
Subject: [PATCH 6.12.y 2/2] gpiolib: fix race condition for gdev->srcu
Date: Wed, 15 Apr 2026 13:15:41 +0200 [thread overview]
Message-ID: <20260415-6-12-gpiolib-cve-2026-22986-v1-2-3a7a6de332eb@cherry.de> (raw)
In-Reply-To: <20260415-6-12-gpiolib-cve-2026-22986-v1-0-3a7a6de332eb@cherry.de>
From: Paweł Narewski <pawel.narewski@nokia.com>
[ Upstream commit a7ac22d53d0990152b108c3f4fe30df45fcb0181 ]
If two drivers were calling gpiochip_add_data_with_key(), one may be
traversing the srcu-protected list in gpio_name_to_desc(), meanwhile
other has just added its gdev in gpiodev_add_to_list_unlocked().
This creates a non-mutexed and non-protected timeframe, when one
instance is dereferencing and using &gdev->srcu, before the other
has initialized it, resulting in crash:
[ 4.935481] Unable to handle kernel paging request at virtual address ffff800272bcc000
[ 4.943396] Mem abort info:
[ 4.943400] ESR = 0x0000000096000005
[ 4.943403] EC = 0x25: DABT (current EL), IL = 32 bits
[ 4.943407] SET = 0, FnV = 0
[ 4.943410] EA = 0, S1PTW = 0
[ 4.943413] FSC = 0x05: level 1 translation fault
[ 4.943416] Data abort info:
[ 4.943418] ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
[ 4.946220] CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[ 4.955261] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[ 4.955268] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000038e6c000
[ 4.961449] [ffff800272bcc000] pgd=0000000000000000
[ 4.969203] , p4d=1000000039739003
[ 4.979730] , pud=0000000000000000
[ 4.980210] phandle (CPU): 0x0000005e, phandle (BE): 0x5e000000 for node "reset"
[ 4.991736] Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
...
[ 5.121359] pc : __srcu_read_lock+0x44/0x98
[ 5.131091] lr : gpio_name_to_desc+0x60/0x1a0
[ 5.153671] sp : ffff8000833bb430
[ 5.298440]
[ 5.298443] Call trace:
[ 5.298445] __srcu_read_lock+0x44/0x98
[ 5.309484] gpio_name_to_desc+0x60/0x1a0
[ 5.320692] gpiochip_add_data_with_key+0x488/0xf00
5.946419] ---[ end trace 0000000000000000 ]---
Move initialization code for gdev fields before it is added to
gpio_devices, with adjacent initialization code.
Adjust goto statements to reflect modified order of operations
Fixes: 47d8b4c1d868 ("gpio: add SRCU infrastructure to struct gpio_device")
Reviewed-by: Jakub Lewalski <jakub.lewalski@nokia.com>
Signed-off-by: Paweł Narewski <pawel.narewski@nokia.com>
[Bartosz: fixed a build issue, removed stray newline]
Link: https://lore.kernel.org/r/20251224082641.10769-1-bartosz.golaszewski@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
[missing commit fcc8b637c542 ("gpiolib: switch the line state notifier
to atomic"), commit dcb73cbaaeb3 ("gpio: cdev: use raw notifier for
line state events") and commit d4f335b410dd ("gpiolib: rename GPIO chip
printk macros") in 6.12.y.
Both notifiers as well as both srcu inits are moved before the
scoped_guard, following same logic as in a7ac22d53d09.
Rest is changes to git context only.]
Cc: stable@vger.kernel.org # 6.12
Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de>
---
drivers/gpio/gpiolib.c | 38 +++++++++++++++++++-------------------
1 file changed, 19 insertions(+), 19 deletions(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 3f9019cc832ac..5c8cd81656963 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -988,6 +988,17 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
gdev->ngpio = gc->ngpio;
gdev->can_sleep = gc->can_sleep;
+ BLOCKING_INIT_NOTIFIER_HEAD(&gdev->line_state_notifier);
+ BLOCKING_INIT_NOTIFIER_HEAD(&gdev->device_notifier);
+
+ ret = init_srcu_struct(&gdev->srcu);
+ if (ret)
+ goto err_free_label;
+
+ ret = init_srcu_struct(&gdev->desc_srcu);
+ if (ret)
+ goto err_cleanup_gdev_srcu;
+
scoped_guard(mutex, &gpio_devices_lock) {
/*
* TODO: this allocates a Linux GPIO number base in the global
@@ -1002,7 +1013,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
if (base < 0) {
ret = base;
base = 0;
- goto err_free_label;
+ goto err_cleanup_desc_srcu;
}
/*
@@ -1022,21 +1033,10 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
ret = gpiodev_add_to_list_unlocked(gdev);
if (ret) {
chip_err(gc, "GPIO integer space overlap, cannot add chip\n");
- goto err_free_label;
+ goto err_cleanup_desc_srcu;
}
}
- BLOCKING_INIT_NOTIFIER_HEAD(&gdev->line_state_notifier);
- BLOCKING_INIT_NOTIFIER_HEAD(&gdev->device_notifier);
-
- ret = init_srcu_struct(&gdev->srcu);
- if (ret)
- goto err_remove_from_list;
-
- ret = init_srcu_struct(&gdev->desc_srcu);
- if (ret)
- goto err_cleanup_gdev_srcu;
-
#ifdef CONFIG_PINCTRL
INIT_LIST_HEAD(&gdev->pin_ranges);
#endif
@@ -1046,11 +1046,11 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
ret = gpiochip_set_names(gc);
if (ret)
- goto err_cleanup_desc_srcu;
+ goto err_remove_from_list;
ret = gpiochip_init_valid_mask(gc);
if (ret)
- goto err_cleanup_desc_srcu;
+ goto err_remove_from_list;
for (desc_index = 0; desc_index < gc->ngpio; desc_index++) {
struct gpio_desc *desc = &gdev->descs[desc_index];
@@ -1117,10 +1117,6 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
of_gpiochip_remove(gc);
err_free_valid_mask:
gpiochip_free_valid_mask(gc);
-err_cleanup_desc_srcu:
- cleanup_srcu_struct(&gdev->desc_srcu);
-err_cleanup_gdev_srcu:
- cleanup_srcu_struct(&gdev->srcu);
err_remove_from_list:
scoped_guard(mutex, &gpio_devices_lock)
list_del_rcu(&gdev->list);
@@ -1130,6 +1126,10 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
gpio_device_put(gdev);
goto err_print_message;
}
+err_cleanup_desc_srcu:
+ cleanup_srcu_struct(&gdev->desc_srcu);
+err_cleanup_gdev_srcu:
+ cleanup_srcu_struct(&gdev->srcu);
err_free_label:
kfree_const(gdev->label);
err_free_descs:
--
2.53.0
next prev parent reply other threads:[~2026-04-15 11:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-15 11:15 [PATCH 6.12.y 0/2] gpiolib: backport fa17f749ee5b and a7ac22d53d09 Quentin Schulz
2026-04-15 11:15 ` [PATCH 6.12.y 1/2] gpiolib: unify two loops initializing GPIO descriptors Quentin Schulz
2026-04-15 11:15 ` Quentin Schulz [this message]
2026-04-20 9:26 ` [PATCH 6.12.y 0/2] gpiolib: backport fa17f749ee5b and a7ac22d53d09 Bartosz Golaszewski
2026-04-20 13:21 ` Sasha Levin
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