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drm/i915/cmdparser: Check reg_table_count before derefencing.

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The find_reg function was assuming that there is always at least one table in
reg_tables. It is not always true.

In case of VCS or VECS, the reg_tables is NULL and reg_table_count is 0,
implying that no register-accessing commands are allowed. However, the command
tables include commands such as MI_STORE_REGISTER_MEM. When trying to check
such command, the find_reg would dereference NULL pointer.

Now it will just return NULL meaning that the register was not found and the
command will be rejected.

Fixes: 76ff480ec9 ("drm/i915/cmdparser: Use binary search for faster register lookup")
Signed-off-by: Michal Srb <msrb@suse.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180205142916.27092-2-msrb@suse.com
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180205160438.3267-1-chris@chris-wilson.co.uk
register lookup")
(cherry picked from commit 2f265fad97)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Michal Srb 2018-02-05 16:04:37 +00:00 committed by Rodrigo Vivi
parent 5e1df40f40
commit b18224e95c
1 changed files with 2 additions and 2 deletions
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4
drivers/gpu/drm/i915/i915_cmd_parser.c
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@ -1032,7 +1032,7 @@ find_reg(const struct intel_engine_cs *engine, bool is_master, u32 addr)
const struct drm_i915_reg_table *table = engine->reg_tables;
int count = engine->reg_table_count;
do {
for (; count > 0; ++table, --count) {
if (!table->master || is_master) {
const struct drm_i915_reg_descriptor *reg;
@ -1040,7 +1040,7 @@ find_reg(const struct intel_engine_cs *engine, bool is_master, u32 addr)
if (reg != NULL)
return reg;
}
} while (table++, --count);
}
return NULL;
}