On 7/17/2024 5:11 PM, Cavitt, Jonathan wrote:
-----Original Message-----
From: Nirmoy Das <nirmoy.das@xxxxxxxxxxxxxxx>
Sent: Wednesday, July 17, 2024 8:06 AM
To: Cavitt, Jonathan <jonathan.cavitt@xxxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: Gupta, saurabhg <saurabhg.gupta@xxxxxxxxx>; dan.carpenter@xxxxxxxxxx; chris.p.wilson@xxxxxxxxxxxxxxx; Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
Subject: Re: [PATCH] drm/i915: Allow NULL memory region
On 7/12/2024 11:41 PM, Jonathan Cavitt wrote:
Prevent a NULL pointer access in intel_memory_regions_hw_probe.
Fixes: 05da7d9f717b ("drm/i915/gem: Downgrade stolen lmem setup warning")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_memory_region.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_memory_region.c b/drivers/gpu/drm/i915/intel_memory_region.c
index 172dfa7c3588b..d40ee1b42110a 100644
--- a/drivers/gpu/drm/i915/intel_memory_region.c
+++ b/drivers/gpu/drm/i915/intel_memory_region.c
@@ -368,8 +368,10 @@ int intel_memory_regions_hw_probe(struct drm_i915_private *i915)
goto out_cleanup;
}
- mem->id = i;
- i915->mm.regions[i] = mem;
There is a check for mem just before that. You could use
IS_ERR_OR_NULL(mem) instead of IS_ERR().
I think you're referring to the "goto out_cleanup" path?
Yes.
mem being NULL is a valid use case, so we
shouldn't take the error path when it's observed.
Not an error path if you return expected/correct value.
You could do
diff --git a/drivers/gpu/drm/i915/intel_memory_region.c b/drivers/gpu/drm/i915/intel_memory_region.c
index 172dfa7c3588..41ef7fdfa69b 100644
--- a/drivers/gpu/drm/i915/intel_memory_region.c
+++ b/drivers/gpu/drm/i915/intel_memory_region.c
@@ -362,9 +362,10 @@ int intel_memory_regions_hw_probe(struct drm_i915_private *i915)
if (IS_ERR(mem)) {
err = PTR_ERR(mem);
- drm_err(&i915->drm,
- "Failed to setup region(%d) type=%d\n",
- err, type);
+ if (err)
+ drm_err(&i915->drm,
+ "Failed to setup region(%d) type=%d\n",
+ err, type);
goto out_cleanup;
}
PTR_ERR(NULL) should be 0 I think and could even add a info saying skipping setting up that reason.
Regards,
Nirmoy
-Jonathan Cavitt
Regards,
Nirmoy
+ if (mem) { /* Skip on non-fatal errors */
+ mem->id = i;
+ i915->mm.regions[i] = mem;
+ }
}
for (i = 0; i < ARRAY_SIZE(i915->mm.regions); i++) {
