[PATCH 02/10] EDAC/altera: Fix use-after-free in error paths

[Dinh Nguyen <dinguyen@kernel.org>]

In both altr_edac_a10_device_add() and altr_portb_setup(), the error path
freed dci before releasing the devres group. Since the managed SB/DB IRQ
handlers use altdev(dci->pvt_info) as their data, an IRQ firing between
freeing dci and unregistering the IRQs could dereference freed memory.

Release the devres group first so the managed IRQs are unregistered
before dci is freed.

Assisted-by: Cursor:claude-4.8-opus
Fixes: 911049845d70 ("EDAC, altera: Add Arria10 SD-MMC EDAC support")
Fixes: 588cb03ea208 ("EDAC, altera: Add Arria10 L2 Cache ECC handling")
Closes: https://sashiko.dev/#/patchset/20260719211238.589402-1-rosenp%40gmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
---
 drivers/edac/altera_edac.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/edac/altera_edac.c b/drivers/edac/altera_edac.c
index d6ca68d74f78a..34b33298cf86e 100644
--- a/drivers/edac/altera_edac.c
+++ b/drivers/edac/altera_edac.c
@@ -1625,8 +1625,13 @@ static int altr_portb_setup(struct altr_edac_device_dev *device)
 	return 0;
 
 err_release_group_1:
-	edac_device_free_ctl_info(dci);
+	/*
+	 * Release the devres group first so the managed IRQs are
+	 * unregistered before dci (which contains the IRQ handler's
+	 * data via dci->pvt_info) is freed, avoiding a use-after-free.
+	 */
 	devres_release_group(device->edac->dev, altr_portb_setup);
+	edac_device_free_ctl_info(dci);
 	edac_printk(KERN_ERR, EDAC_DEVICE,
 		    "%s:Error setting up EDAC device: %d\n", ecc_name, rc);
 	return rc;
@@ -2029,9 +2034,17 @@ static int altr_edac_a10_device_add(struct altr_arria10_edac *edac,
 	return 0;
 
 err_release_group1:
+	/*
+	 * Release the devres group first so the managed IRQs are
+	 * unregistered before dci (which contains the IRQ handler's
+	 * data via dci->pvt_info) is freed, avoiding a use-after-free.
+	 */
+	devres_release_group(edac->dev, NULL);
 	edac_device_free_ctl_info(dci);
+	goto err_print;
 err_release_group:
 	devres_release_group(edac->dev, NULL);
+err_print:
 	edac_printk(KERN_ERR, EDAC_DEVICE,
 		    "%s:Error setting up EDAC device: %d\n", ecc_name, rc);
 
-- 
2.42.0.411.g813d9a9188