From 7efb1b19b3414d7dec792f39e1c1a7db57a23961 Mon Sep 17 00:00:00 2001 From: Yann Droneaud Date: Wed, 11 Dec 2013 23:01:47 +0100 Subject: [PATCH] IB/uverbs: Check reserved field in extended command header As noted by Daniel Vetter in its article "Botching up ioctls"[1] "Check *all* unused fields and flags and all the padding for whether it's 0, and reject the ioctl if that's not the case. Otherwise your nice plan for future extensions is going right down the gutters since someone *will* submit an ioctl struct with random stack garbage in the yet unused parts. Which then bakes in the ABI that those fields can never be used for anything else but garbage." It's important to ensure that reserved fields are set to known value, so that it will be possible to use them latter to extend the ABI. The same reasonning apply to comp_mask field present in newer uverbs command: per commit 22878dbc9173 ("IB/core: Better checking of userspace values for receive flow steering"), unsupported values in comp_mask are rejected. [1] http://blog.ffwll.ch/2013/11/botching-up-ioctls.html Link: http://marc.info/?i=cover.1386798254.git.ydroneaud@opteya.com> Signed-off-by: Yann Droneaud Signed-off-by: Roland Dreier --- drivers/infiniband/core/uverbs_main.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c index 699463bbfd2d..ac2305d8d7c4 100644 --- a/drivers/infiniband/core/uverbs_main.c +++ b/drivers/infiniband/core/uverbs_main.c @@ -668,6 +668,9 @@ static ssize_t ib_uverbs_write(struct file *filp, const char __user *buf, if ((hdr.in_words + ex_hdr.provider_in_words) * 8 != count) return -EINVAL; + if (ex_hdr.cmd_hdr_reserved) + return -EINVAL; + if (ex_hdr.response) { if (!hdr.out_words && !ex_hdr.provider_out_words) return -EINVAL; -- 2.30.2