4.9-stable review patch. If anyone has any objections, please let me know.
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From: "Gustavo A. R. Silva" garsilva@embeddedor.com
[ Upstream commit 63f1e05f7fe9ca509c60154d6a833abf96eecdc9 ]
df->governor is being dereferenced before it is null checked, hence there is a potential null pointer dereference.
Notice that df->governor is being null checked at line 1004: if (df->governor) {, which implies it might be null.
Fix this by null checking df->governor before dereferencing it.
Addresses-Coverity-ID: 1401988 ("Dereference before null check") Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs") Signed-off-by: Gustavo A. R. Silva garsilva@embeddedor.com Reviewed-by: Chanwoo Choi cw00.choi@samsung.com Signed-off-by: MyungJoo Ham myungjoo.ham@samsung.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/devfreq/devfreq.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -943,7 +943,8 @@ static ssize_t governor_store(struct dev if (df->governor == governor) { ret = 0; goto out; - } else if (df->governor->immutable || governor->immutable) { + } else if ((df->governor && df->governor->immutable) || + governor->immutable) { ret = -EINVAL; goto out; }