broadcom/vc4: Fix use-after-free when deleting a program.

By leaving the compiled shader in the context's stage state, the next
compile of a new FS would look in the old compiled FS for figuring out
whether to set various dirty flags for the VS compile.  Clear out the
pointer when deleting the program, and make sure that we always mark the
state as dirty if the previous program had been lost.  Fixes valgrind
warnings on glsl-max-varyings.

Fixes: 2350569a78c6 ("vc4: Avoid VS shader recompiles by keeping a set of FS inputs seen so far.")
(cherry picked from commit 3752ad28f23fc8136f75104b6ac4572341a05467)

1 files changed, 15 insertions, 6 deletions

diff --git a/src/gallium/drivers/vc4/vc4_program.c b/src/gallium/drivers/vc4/vc4_program.c
index 59368734d08..65a2bca718a 100644
--- a/src/gallium/drivers/vc4/vc4_program.c
+++ b/src/gallium/drivers/vc4/vc4_program.c
@@ -2763,11 +2763,11 @@ vc4_update_compiled_fs(struct vc4_context *vc4, uint8_t prim_mode)
         vc4->dirty |= VC4_DIRTY_COMPILED_FS;
 
         if (vc4->rasterizer->base.flatshade &&
-            old_fs && vc4->prog.fs->color_inputs != old_fs->color_inputs) {
+            (!old_fs || vc4->prog.fs->color_inputs != old_fs->color_inputs)) {
                 vc4->dirty |= VC4_DIRTY_FLAT_SHADE_FLAGS;
         }
 
-        if (old_fs && vc4->prog.fs->fs_inputs != old_fs->fs_inputs)
+        if (!old_fs || vc4->prog.fs->fs_inputs != old_fs->fs_inputs)
                 vc4->dirty |= VC4_DIRTY_FS_INPUTS;
 }
 
@@ -2877,6 +2877,7 @@ fs_inputs_compare(const void *key1, const void *key2)
 
 static void
 delete_from_cache_if_matches(struct hash_table *ht,
+                             struct vc4_compiled_shader **last_compile,
                              struct hash_entry *entry,
                              struct vc4_uncompiled_shader *so)
 {
@@ -2886,6 +2887,10 @@ delete_from_cache_if_matches(struct hash_table *ht,
                 struct vc4_compiled_shader *shader = entry->data;
                 _mesa_hash_table_remove(ht, entry);
                 vc4_bo_unreference(&shader->bo);
+
+                if (shader == *last_compile)
+                        *last_compile = NULL;
+
                 ralloc_free(shader);
         }
 }
@@ -2897,10 +2902,14 @@ vc4_shader_state_delete(struct pipe_context *pctx, void *hwcso)
         struct vc4_uncompiled_shader *so = hwcso;
 
         struct hash_entry *entry;
-        hash_table_foreach(vc4->fs_cache, entry)
-                delete_from_cache_if_matches(vc4->fs_cache, entry, so);
-        hash_table_foreach(vc4->vs_cache, entry)
-                delete_from_cache_if_matches(vc4->vs_cache, entry, so);
+        hash_table_foreach(vc4->fs_cache, entry) {
+                delete_from_cache_if_matches(vc4->fs_cache, &vc4->prog.fs,
+                                             entry, so);
+        }
+        hash_table_foreach(vc4->vs_cache, entry) {
+                delete_from_cache_if_matches(vc4->vs_cache, &vc4->prog.vs,
+                                             entry, so);
+        }
 
         ralloc_free(so->base.ir.nir);
         free(so);