From: Viresh Kumar <viresh.kumar@xxxxxxxxxx> [ Upstream commit 7ee23491b39259ae83899dd93b2a29ef0f22f0a7 ] The permissions of the read-only or write-only sysfs files can be changed (as root) and the user can then try to read a write-only file or write to a read-only file which will lead to kernel crash here. Protect against that by always validating the show/store callbacks. Link: https://lore.kernel.org/r/d45cc26361a174ae12dbb86c994ef334d257924b.1573096807.git.viresh.kumar@xxxxxxxxxx Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx> Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/infiniband/hw/qib/qib_sysfs.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/infiniband/hw/qib/qib_sysfs.c b/drivers/infiniband/hw/qib/qib_sysfs.c index 3926be78036ee..568b21eb6ea15 100644 --- a/drivers/infiniband/hw/qib/qib_sysfs.c +++ b/drivers/infiniband/hw/qib/qib_sysfs.c @@ -301,6 +301,9 @@ static ssize_t qib_portattr_show(struct kobject *kobj, struct qib_pportdata *ppd = container_of(kobj, struct qib_pportdata, pport_kobj); + if (!pattr->show) + return -EIO; + return pattr->show(ppd, buf); } @@ -312,6 +315,9 @@ static ssize_t qib_portattr_store(struct kobject *kobj, struct qib_pportdata *ppd = container_of(kobj, struct qib_pportdata, pport_kobj); + if (!pattr->store) + return -EIO; + return pattr->store(ppd, buf, len); } -- 2.20.1
