This is a note to let you know that I've just added the patch titled RDMA/qib: Validate ->show()/store() callbacks before calling them to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: rdma-qib-validate-show-store-callbacks-before-calling-them.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 7ee23491b39259ae83899dd93b2a29ef0f22f0a7 Mon Sep 17 00:00:00 2001 From: Viresh Kumar <viresh.kumar@xxxxxxxxxx> Date: Thu, 7 Nov 2019 08:50:25 +0530 Subject: RDMA/qib: Validate ->show()/store() callbacks before calling them From: Viresh Kumar <viresh.kumar@xxxxxxxxxx> commit 7ee23491b39259ae83899dd93b2a29ef0f22f0a7 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/infiniband/hw/qib/qib_sysfs.c | 6 ++++++ 1 file changed, 6 insertions(+) --- 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 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 struct qib_pportdata *ppd = container_of(kobj, struct qib_pportdata, pport_kobj); + if (!pattr->store) + return -EIO; + return pattr->store(ppd, buf, len); } Patches currently in stable-queue which might be from viresh.kumar@xxxxxxxxxx are queue-4.4/rdma-qib-validate-show-store-callbacks-before-calling-them.patch