Re: [Intel-gfx] [PATCH] drm/i915: zero fill vma name buffer
From: Tim Gardner
Date: Thu Sep 16 2021 - 07:37:55 EST
On 9/16/21 4:43 AM, Jani Nikula wrote:
On Thu, 16 Sep 2021, Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx> wrote:
On 15/09/2021 20:23, Tim Gardner wrote:
In capture_vma() Coverity complains of a possible buffer overrun. Even
though this is a static function where all call sites can be checked,
limiting the copy length could save some future grief.
CID 93300 (#1 of 1): Copy into fixed size buffer (STRING_OVERFLOW)
4. fixed_size_dest: You might overrun the 16-character fixed-size string c->name
by copying name without checking the length.
5. parameter_as_source: Note: This defect has an elevated risk because the
source argument is a parameter of the current function.
1326 strcpy(c->name, name);
Fix any possible overflows by using strncpy(). Zero fill the name buffer to
guarantee ASCII string NULL termination.
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Tim Gardner <tim.gardner@xxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gpu_error.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 9cf6ac575de1..154df174e2d7 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1297,10 +1297,11 @@ static bool record_context(struct i915_gem_context_coredump *e,
return simulated;
}
+#define VMA_NAME_LEN 16
struct intel_engine_capture_vma {
struct intel_engine_capture_vma *next;
struct i915_vma *vma;
- char name[16];
+ char name[VMA_NAME_LEN];
};
static struct intel_engine_capture_vma *
@@ -1314,7 +1315,7 @@ capture_vma(struct intel_engine_capture_vma *next,
if (!vma)
return next;
- c = kmalloc(sizeof(*c), gfp);
+ c = kzalloc(sizeof(*c), gfp);
if (!c)
return next;
@@ -1323,7 +1324,7 @@ capture_vma(struct intel_engine_capture_vma *next,
return next;
}
- strcpy(c->name, name);
+ strncpy(c->name, name, VMA_NAME_LEN-1);
GCC is supposed to catch any problems here as you say in the commit message.
But to fix I suggest a single line change to strlcpy(c->name, name,
sizeof(c->name)) which always null terminates as bonus.
strscpy() is preferred over both strncpy() and strlcpy(). :)
BR,
Jani.
Good call. v2 on the way.
rtg
Probably same in i915_vma_coredump_create() which with strncpy would
have a theoretical chance of attempting to copy over a
non-null-terminated string.
Regards,
Tvrtko
c->vma = vma; /* reference held while active */
c->next = next;
--
-----------
Tim Gardner
Canonical, Inc