From: Jason Ekstrand <jason@jlekstrand.net>
To: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
Jason Ekstrand <jason@jlekstrand.net>
Subject: [PATCH 20/31] drm/i915/gem: Make an alignment check more sensible
Date: Tue, 8 Jun 2021 23:36:02 -0500 [thread overview]
Message-ID: <20210609043613.102962-21-jason@jlekstrand.net> (raw)
In-Reply-To: <20210609043613.102962-1-jason@jlekstrand.net>
What we really want to check is that size of the engines array, i.e.
args->size - sizeof(*user) is divisible by the element size, i.e.
sizeof(*user->engines) because that's what's required for computing the
array length right below the check. However, we're currently not doing
this and instead doing a compile-time check that sizeof(*user) is
divisible by sizeof(*user->engines) and avoiding the subtraction. As
far as I can tell, the only reason for the more confusing pair of checks
is to avoid a single subtraction of a constant.
The other thing the BUILD_BUG_ON might be trying to implicitly check is
that offsetof(user->engines) == sizeof(*user) and we don't have any
weird padding throwing us off. However, that's not the check it's doing
and it's not even a reliable way to do that check.
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
drivers/gpu/drm/i915/gem/i915_gem_context.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 8df284dcfcf3a..de2601c81f603 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -1763,9 +1763,8 @@ set_engines(struct i915_gem_context *ctx,
goto replace;
}
- BUILD_BUG_ON(!IS_ALIGNED(sizeof(*user), sizeof(*user->engines)));
if (args->size < sizeof(*user) ||
- !IS_ALIGNED(args->size, sizeof(*user->engines))) {
+ !IS_ALIGNED(args->size - sizeof(*user), sizeof(*user->engines))) {
drm_dbg(&i915->drm, "Invalid size for engine array: %d\n",
args->size);
return -EINVAL;
--
2.31.1
next prev parent reply other threads:[~2021-06-09 4:37 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 4:35 [PATCH 00/31] drm/i915/gem: ioctl clean-ups (v6) Jason Ekstrand
2021-06-09 4:35 ` [PATCH 01/31] drm/i915: Drop I915_CONTEXT_PARAM_RINGSIZE Jason Ekstrand
2021-06-09 4:35 ` [PATCH 02/31] drm/i915: Stop storing the ring size in the ring pointer (v2) Jason Ekstrand
2021-06-09 4:35 ` [PATCH 03/31] drm/i915: Drop I915_CONTEXT_PARAM_NO_ZEROMAP Jason Ekstrand
2021-06-09 4:35 ` [PATCH 04/31] drm/i915/gem: Set the watchdog timeout directly in intel_context_set_gem (v2) Jason Ekstrand
2021-06-09 4:35 ` [PATCH 05/31] drm/i915/gem: Return void from context_apply_all Jason Ekstrand
2021-06-09 4:35 ` [PATCH 06/31] drm/i915: Drop the CONTEXT_CLONE API (v2) Jason Ekstrand
2021-06-09 4:35 ` [PATCH 07/31] drm/i915: Implement SINGLE_TIMELINE with a syncobj (v4) Jason Ekstrand
2021-06-09 4:35 ` [PATCH 08/31] drm/i915: Drop getparam support for I915_CONTEXT_PARAM_ENGINES Jason Ekstrand
2021-06-09 4:35 ` [PATCH 09/31] drm/i915/gem: Disallow bonding of virtual engines (v3) Jason Ekstrand
2021-06-09 4:35 ` [PATCH 10/31] drm/i915/gem: Remove engine auto-magic with FENCE_SUBMIT (v2) Jason Ekstrand
2021-06-09 4:35 ` [PATCH 11/31] drm/i915/request: Remove the hook from await_execution Jason Ekstrand
2021-06-09 4:35 ` [PATCH 12/31] drm/i915/gem: Disallow creating contexts with too many engines Jason Ekstrand
2021-06-09 4:35 ` [PATCH 13/31] drm/i915: Stop manually RCU banging in reset_stats_ioctl (v2) Jason Ekstrand
2021-06-09 4:35 ` [PATCH 14/31] drm/i915/gem: Add a separate validate_priority helper Jason Ekstrand
2021-06-09 4:35 ` [PATCH 15/31] drm/i915: Add gem/i915_gem_context.h to the docs Jason Ekstrand
2021-06-09 4:35 ` [PATCH 16/31] drm/i915/gem: Add an intermediate proto_context struct (v4) Jason Ekstrand
2021-06-09 11:28 ` [Intel-gfx] " Daniel Vetter
2021-06-09 16:00 ` Jason Ekstrand
2021-06-10 16:44 ` Daniel Vetter
2021-06-10 16:53 ` Jason Ekstrand
2021-06-09 4:35 ` [PATCH 17/31] drm/i915/gem: Rework error handling in default_engines Jason Ekstrand
2021-06-09 4:36 ` [PATCH 18/31] drm/i915/gem: Optionally set SSEU in intel_context_set_gem Jason Ekstrand
2021-06-09 4:36 ` [PATCH 19/31] drm/i915: Add an i915_gem_vm_lookup helper Jason Ekstrand
2021-06-09 4:36 ` Jason Ekstrand [this message]
2021-06-09 4:36 ` [PATCH 21/31] drm/i915/gem: Use the proto-context to handle create parameters (v3) Jason Ekstrand
2021-06-09 4:36 ` [PATCH 22/31] drm/i915/gem: Return an error ptr from context_lookup Jason Ekstrand
2021-06-09 4:36 ` [PATCH 23/31] drm/i915/gt: Drop i915_address_space::file (v2) Jason Ekstrand
2021-06-09 4:36 ` [PATCH 24/31] drm/i915/gem: Delay context creation (v2) Jason Ekstrand
2021-06-09 8:25 ` [Intel-gfx] " kernel test robot
2021-06-09 11:38 ` kernel test robot
2021-06-09 11:44 ` kernel test robot
2021-06-09 4:36 ` [PATCH 25/31] drm/i915/gem: Don't allow changing the VM on running contexts (v2) Jason Ekstrand
2021-06-09 7:39 ` [Intel-gfx] " kernel test robot
2021-06-09 11:34 ` Daniel Vetter
2021-06-09 11:34 ` Daniel Vetter
2021-06-09 16:06 ` Jason Ekstrand
2021-06-09 4:36 ` [PATCH 26/31] drm/i915/gem: Don't allow changing the engine set " Jason Ekstrand
2021-06-09 4:36 ` [PATCH 27/31] drm/i915/selftests: Take a VM in kernel_context() Jason Ekstrand
2021-06-09 4:36 ` [PATCH 28/31] i915/gem/selftests: Assign the VM at context creation in igt_shared_ctx_exec Jason Ekstrand
2021-06-09 4:36 ` [PATCH 29/31] drm/i915/gem: Roll all of context creation together Jason Ekstrand
2021-06-09 4:36 ` [PATCH 30/31] drm/i915: Finalize contexts in GEM_CONTEXT_CREATE on version 13+ Jason Ekstrand
2021-06-09 10:13 ` [Intel-gfx] " kernel test robot
2021-06-09 11:38 ` Daniel Vetter
2021-06-09 4:36 ` [PATCH 31/31] drm/i915: Drop some RCU usage around context VMs Jason Ekstrand
2021-06-09 11:41 ` [Intel-gfx] " Daniel Vetter
2021-06-09 16:07 ` Jason Ekstrand
-- strict thread matches above, loose matches on Subject: below --
2021-06-09 17:43 [PATCH 00/31] drm/i915/gem: ioctl clean-ups (v6) Jason Ekstrand
2021-06-09 17:44 ` [PATCH 20/31] drm/i915/gem: Make an alignment check more sensible Jason Ekstrand
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