Hi Guocai,

On 13/12/24 16:01, guocai.he.cn@windriver.com wrote:

From: Ian Ray ian.ray@gehealthcare.com

[ Upstream commit bfc6444b57dc7186b6acc964705d7516cbaf3904 ]

Ensure that `i2c_lock' is held when setting interrupt latch and mask in pca953x_irq_bus_sync_unlock() in order to avoid races.

The other (non-probe) call site pca953x_gpio_set_multiple() ensures the lock is held before calling pca953x_write_regs().

The problem occurred when a request raced against irq_bus_sync_unlock() approximately once per thousand reboots on an i.MX8MP based system.

• Normal case

  0-0022: write register AI|3a {03,02,00,00,01} Input latch P0 0-0022: write register AI|49 {fc,fd,ff,ff,fe} Interrupt mask P0 0-0022: write register AI|08 {ff,00,00,00,00} Output P3 0-0022: write register AI|12 {fc,00,00,00,00} Config P3

• Race case

  0-0022: write register AI|08 {ff,00,00,00,00} Output P3 0-0022: write register AI|08 {03,02,00,00,01} *** Wrong register *** 0-0022: write register AI|12 {fc,00,00,00,00} Config P3 0-0022: write register AI|49 {fc,fd,ff,ff,fe} Interrupt mask P0

Signed-off-by: Ian Ray ian.ray@gehealthcare.com Link: https://lore.kernel.org/r/20240620042915.2173-1-ian.ray@gehealthcare.com Signed-off-by: Bartosz Golaszewski bartosz.golaszewski@linaro.org Signed-off-by: Guocai He guocai.he.cn@windriver.com

---

This commit is to solve the CVE-2024-42253. Please merge this commit to linux-5.15.y.

drivers/gpio/gpio-pca953x.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c index 4860bf3b7e00..4e97b6ae4f72 100644 --- a/drivers/gpio/gpio-pca953x.c +++ b/drivers/gpio/gpio-pca953x.c @@ -672,6 +672,8 @@ static void pca953x_irq_bus_sync_unlock(struct irq_data *d) int level; if (chip->driver_data & PCA_PCAL) {

• guard(mutex)(&chip->i2c_lock);
  

This wouldn't compile on 5.15.y

We don't have scope based locking backported to 5.15.y.

drivers/gpio/gpio-pca953x.c: In function ‘pca953x_irq_bus_sync_unlock’: drivers/gpio/gpio-pca953x.c:675:17: error: implicit declaration of function ‘guard’ [-Werror=implicit-function-declaration] 675 | guard(mutex)(&chip->i2c_lock); | ^~~~~ drivers/gpio/gpio-pca953x.c:675:23: error: ‘mutex’ undeclared (first use in this function) 675 | guard(mutex)(&chip->i2c_lock); | ^~~~~ drivers/gpio/gpio-pca953x.c:675:23: note: each undeclared identifier is reported only once for each function it appears in cc1: all warnings being treated as errors

Thanks, Harshit

• /* Enable latch on interrupt-enabled inputs */ pca953x_write_regs(chip, PCAL953X_IN_LATCH, chip->irq_mask);

[ Sasha's backport helper bot ]

Hi,

The upstream commit SHA1 provided is correct: bfc6444b57dc7186b6acc964705d7516cbaf3904

WARNING: Author mismatch between patch and upstream commit: Backport author: guocai.he.cn@windriver.com Commit author: Ian Ray ian.ray@gehealthcare.com

Status in newer kernel trees: 6.12.y | Present (exact SHA1) 6.6.y | Present (different SHA1: e2ecdddca80d) 6.1.y | Present (different SHA1: 58a5c93bd1a6) 5.15.y | Not found

Note: The patch differs from the upstream commit: --- 1: bfc6444b57dc7 ! 1: 3812c0bc93e5e gpio: pca953x: fix pca953x_irq_bus_sync_unlock race @@ Metadata ## Commit message ## gpio: pca953x: fix pca953x_irq_bus_sync_unlock race

+ [ Upstream commit bfc6444b57dc7186b6acc964705d7516cbaf3904 ] + Ensure that `i2c_lock' is held when setting interrupt latch and mask in pca953x_irq_bus_sync_unlock() in order to avoid races.

@@ Commit message Signed-off-by: Ian Ray ian.ray@gehealthcare.com Link: https://lore.kernel.org/r/20240620042915.2173-1-ian.ray@gehealthcare.com Signed-off-by: Bartosz Golaszewski bartosz.golaszewski@linaro.org + Signed-off-by: Guocai He guocai.he.cn@windriver.com

## drivers/gpio/gpio-pca953x.c ## @@ drivers/gpio/gpio-pca953x.c: static void pca953x_irq_bus_sync_unlock(struct irq_data *d) ---

Results of testing on various branches:

| Branch | Patch Apply | Build Test | |---------------------------|-------------|------------| | stable/linux-5.15.y | Success | Failed |

Build Errors: Build error for stable/linux-5.15.y: drivers/gpio/gpio-pca953x.c: In function 'pca953x_irq_bus_sync_unlock': drivers/gpio/gpio-pca953x.c:675:17: error: implicit declaration of function 'guard' [-Werror=implicit-function-declaration] 675 | guard(mutex)(&chip->i2c_lock); | ^~~~~ drivers/gpio/gpio-pca953x.c:675:23: error: 'mutex' undeclared (first use in this function) 675 | guard(mutex)(&chip->i2c_lock); | ^~~~~ drivers/gpio/gpio-pca953x.c:675:23: note: each undeclared identifier is reported only once for each function it appears in cc1: some warnings being treated as errors make[2]: *** [scripts/Makefile.build:289: drivers/gpio/gpio-pca953x.o] Error 1 make[2]: Target '__build' not remade because of errors. make[1]: *** [scripts/Makefile.build:552: drivers/gpio] Error 2 make[1]: Target '__build' not remade because of errors. make: *** [Makefile:1906: drivers] Error 2 make: Target '__all' not remade because of errors.