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Subject[PATCH 3.14 098/122] regmap: fix kernel hang on regmap_bulk_write with zero val_count.
Date
3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Quentin Casasnovas <quentin.casasnovas@oracle.com>

Fixes commit 2f06fa04cf35da5c24481da3ac84a2900d0b99c3 which was an
incorrect backported version of commit
d6b41cb06044a7d895db82bdd54f6e4219970510 upstream.

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@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/base/regmap/regmap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1557,8 +1557,10 @@ int regmap_bulk_write(struct regmap *map
} else {
void *wval;

- if (!val_count)
- return -EINVAL;
+ if (!val_count) {
+ ret = -EINVAL;
+ goto out;
+ }

wval = kmemdup(val, val_count * val_bytes, GFP_KERNEL);
if (!wval) {



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