Hi,
While preparing Ksplice rebootless updates for Ubuntu Trusty 3.13.0-40-68,
we've stumbled accross f5942dd ("regmap: fix possible ZERO_SIZE_PTR pointer
dereferencing error.") which fixes a kernel panic but introduces a kernel
hang.
The attached un-tested patch should hopefully fix the issue.
Thanks to Mostafa and Luis for finding the 3.1[234]-stable trees were also
impacted.
Quentin
>From 48a47140d74e7116a14f5300ebcff220176f48ac Mon Sep 17 00:00:00 2001
From: Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx>
Date: Wed, 12 Nov 2014 11:19:23 +0100
Subject: [PATCH] regmap: fix kernel hang on regmap_bulk_write with zero
val_count.
If val_count is zero we return -EINVAL with map->lock_arg locked, which
will deadlock the kernel next time we try to acquire this lock.
This was introduced by f5942dd ("regmap: fix possible ZERO_SIZE_PTR pointer
dereferencing error.") which improperly back-ported d6b41cb0.
This issue was found during review of Ubuntu Trusty 3.13.0-40.68 kernel to
prepare Ksplice rebootless updates.
Fixes: f5942dd ("regmap: fix possible ZERO_SIZE_PTR pointer dereferencing error.")
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx>
---
drivers/base/regmap/regmap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index ebe332c..9e885cf 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1529,8 +1529,10 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
if (val_bytes == 1) {
wval = (void *)val;
} else {
- if (!val_count)
- return -EINVAL;
+ if (!val_count) {
+ ret = -EINVAL;
+ goto out;
+ }
wval = kmemdup(val, val_count * val_bytes, GFP_KERNEL);
if (!wval) {
--
2.0.4