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leds: spi-byte: Initialize device node before access

PATCH RESEND In review Tiffany Yang 4 participants 5 messages Dec 31, 2025 – Jan 8

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Tiffany Yang

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#0 lore raw

PATCH RESEND 1/1 leds: spi-byte: Initialize device node before access

Commit 7f9ab862e05c ("leds: spi-byte: Call of_node_put() on error path") was merged in 6.11 and then backported to stable trees through 5.10. It relocates the line that initializes the variable 'child' to a later point in spi_byte_probe().

Versions < 6.9 do not have commit ccc35ff2fd29 ("leds: spi-byte: Use devm_led_classdev_register_ext()"), which removes a line that reads a property from 'child' before its new initialization point. Consequently, spi_byte_probe() reads from an uninitialized device node in stable kernels 6.6-5.10.

Initialize 'child' before it is first accessed.

Fixes 7f9ab862e05c ("leds: spi-byte: Call of_node_put() on error path")
Signed-off-by Tiffany Yang <[email protected]>

---

As an alternative to moving the initialization of 'child' up, Fedor Pchelkin proposed [1] backporting the change that removes the intermediate access.

[1] https://lore.kernel.org/stable/[email protected]/

---
 drivers/leds/leds-spi-byte.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/leds/leds-spi-byte.c +1 -1
index afe9bff7c7c1..4520df1e2341 100644
@@ -96,6 +96,7 @@ static int spi_byte_probe(struct spi_device *spi)
 	if (!led)
 		return -ENOMEM;
 
+	child = of_get_next_available_child(dev_of_node(dev), NULL);
 	of_property_read_string(child, "label", &name);
 	strscpy(led->name, name, sizeof(led->name));
 	led->spi = spi;

@@ -106,7 +107,6 @@ static int spi_byte_probe(struct spi_device *spi)
 	led->ldev.max_brightness = led->cdef->max_value - led->cdef->off_value;
 	led->ldev.brightness_set_blocking = spi_byte_brightness_set_blocking;
 
-	child = of_get_next_available_child(dev_of_node(dev), NULL);
 	state = of_get_property(child, "default-state", NULL);
 	if (state) {
 		if (!strcmp(state, "on")) {
Signature · 1 line
2.52.0.351.gbe84eed79e-goog
#1 lore raw
Quoted 10 lines · Tiffany Yang

Commit 7f9ab862e05c ("leds: spi-byte: Call of_node_put() on error path") was merged in 6.11 and then backported to stable trees through 5.10. It relocates the line that initializes the variable 'child' to a later point in spi_byte_probe().

Versions < 6.9 do not have commit ccc35ff2fd29 ("leds: spi-byte: Use devm_led_classdev_register_ext()"), which removes a line that reads a property from 'child' before its new initialization point. Consequently, spi_byte_probe() reads from an uninitialized device node in stable kernels 6.6-5.10.

I'm wondering if in long term the easier maintenance will be with that patch also being backported rather than this being applied.

Quoted 1 line

Initialize 'child' before it is first accessed.

Signature · 2 lines
With Best Regards,
Andy Shevchenko
#2 lore raw
Quoted 6 lines · Andy Shevchenko
Quoted 5 lines · Tiffany Yang

Commit 7f9ab862e05c ("leds: spi-byte: Call of_node_put() on error path") was merged in 6.11 and then backported to stable trees through 5.10. It relocates the line that initializes the variable 'child' to a later point in spi_byte_probe().

Quoted 8 lines
Quoted 5 lines

Versions < 6.9 do not have commit ccc35ff2fd29 ("leds: spi-byte: Use devm_led_classdev_register_ext()"), which removes a line that reads a property from 'child' before its new initialization point. Consequently, spi_byte_probe() reads from an uninitialized device node in stable kernels 6.6-5.10.

I'm wondering if in long term the easier maintenance will be with that patch also being backported rather than this being applied.

I agree, that might be simplest.

thanks,

greg k-h

maintainer
#3 lore raw
In reply to Andy Shevchenko
Quoted 6 lines · Andy Shevchenko
Quoted 5 lines · Tiffany Yang

Commit 7f9ab862e05c ("leds: spi-byte: Call of_node_put() on error path") was merged in 6.11 and then backported to stable trees through 5.10. It relocates the line that initializes the variable 'child' to a later point in spi_byte_probe().

Quoted 8 lines
Quoted 5 lines

Versions < 6.9 do not have commit ccc35ff2fd29 ("leds: spi-byte: Use devm_led_classdev_register_ext()"), which removes a line that reads a property from 'child' before its new initialization point. Consequently, spi_byte_probe() reads from an uninitialized device node in stable kernels 6.6-5.10.

I'm wondering if in long term the easier maintenance will be with that patch also being backported rather than this being applied.

Works for me.

Signature · 1 line
Lee Jones [李琼斯]
author
#4 lore raw
Quoted 12 lines · Lee Jones
Quoted 10 lines · Andy Shevchenko
Quoted 1 line · Tiffany Yang

Commit 7f9ab862e05c ("leds: spi-byte: Call of_node_put() on error

path")

Quoted 7 lines

was merged in 6.11 and then backported to stable trees through 5.10. It relocates the line that initializes the variable 'child' to a later point in spi_byte_probe().

Versions < 6.9 do not have commit ccc35ff2fd29 ("leds: spi-byte: Use devm_led_classdev_register_ext()"), which removes a line that reads a property from 'child' before its new initialization point.

Quoted 8 lines
Quoted 6 lines

Consequently,

Quoted 2 lines

spi_byte_probe() reads from an uninitialized device node in stable kernels 6.6-5.10.

I'm wondering if in long term the easier maintenance will be with that patch also being backported rather than this being applied.

Works for me.

Makes sense to me too! Thanks everyone for taking a look, and thanks to Fedor for originally suggesting this :)

Signature · 1 line
Tiffany Y. Yang