From 84b510e22da7926522a257cfe295d3695346a0bd Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 21 May 2018 22:05:30 +0100 Subject: [PATCH] drm/i915/query: Protect tainted function pointer lookup Smatch identifies i915_query_ioctl() as being a potential victim of Spectre due to its use of a tainted user index into a function pointer array. Use array_index_nospec() to defang the user index before using it to lookup the function pointer. Fixes: a446ae2c6e65 ("drm/i915: add query uAPI") Signed-off-by: Chris Wilson Cc: Lionel Landwerlin Cc: Joonas Lahtinen Cc: Tvrtko Ursulin Reviewed-by: Lionel Landwerlin Link: https://patchwork.freedesktop.org/patch/msgid/20180521210530.26008-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_query.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_query.c b/drivers/gpu/drm/i915/i915_query.c index 3ace929dd90f..95f9d179afc4 100644 --- a/drivers/gpu/drm/i915/i915_query.c +++ b/drivers/gpu/drm/i915/i915_query.c @@ -4,6 +4,8 @@ * Copyright © 2018 Intel Corporation */ +#include + #include "i915_drv.h" #include "i915_query.h" #include @@ -111,10 +113,12 @@ int i915_query_ioctl(struct drm_device *dev, void *data, struct drm_file *file) func_idx = item.query_id - 1; - if (func_idx < ARRAY_SIZE(i915_query_funcs)) + ret = -EINVAL; + if (func_idx < ARRAY_SIZE(i915_query_funcs)) { + func_idx = array_index_nospec(func_idx, + ARRAY_SIZE(i915_query_funcs)); ret = i915_query_funcs[func_idx](dev_priv, &item); - else - ret = -EINVAL; + } /* Only write the length back to userspace if they differ. */ if (ret != item.length && put_user(ret, &user_item_ptr->length))