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regmap: fix kernel hang on regmap_bulk_write with zero val_count. 

Fixes commit 2f06fa04cf which was an
incorrect backported version of commit
d6b41cb060 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>
This commit is contained in:
Quentin Casasnovas 2014-11-12 11:19:23 +01:00 committed by Greg Kroah-Hartman
parent 84efcb2025
commit 197b3975f4
1 changed files with 4 additions and 2 deletions
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6
drivers/base/regmap/regmap.c
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@ -1557,8 +1557,10 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
} 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) {