[PATCHv3 4/4] EDAC/altera: Fix use-after-free in error paths

[Dinh Nguyen]

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

Release the devres group first so the managed IRQs are unregistered
before the dci structure 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@xxxxxxxxxxxxxxx
Signed-off-by: Dinh Nguyen <dinguyen@xxxxxxxxxx>
---
v3: No changes
v2: reworked v1 to include only true sashiko hits
---
 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 ccdfb35178b69..4c20fb9261608 100644
--- a/drivers/edac/altera_edac.c
+++ b/drivers/edac/altera_edac.c
@@ -1593,8 +1593,13 @@ 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;
@@ -1997,9 +2002,17 @@ 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