2023-08-21 09:16:45

by Su Hui

[permalink] [raw]
Subject: [PATCH] drm/ast: Avoid possible NULL dereference

smatch error:
drivers/gpu/drm/ast/ast_dp501.c:227 ast_launch_m68k() error:
we previously assumed 'ast->dp501_fw' could be null (see line 223)

when "!ast->dp501_fw" and "ast_load_dp501_microcode(dev) >= 0" is true,
there will be a NULL dereference of 'ast->dp501_fw'.

Fixes: 12f8030e05c6 ("drm/ast: Actually load DP501 firmware when required")
Signed-off-by: Su Hui <[email protected]>
---
drivers/gpu/drm/ast/ast_dp501.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_dp501.c b/drivers/gpu/drm/ast/ast_dp501.c
index 1bc35a992369..d9f3a0786a6f 100644
--- a/drivers/gpu/drm/ast/ast_dp501.c
+++ b/drivers/gpu/drm/ast/ast_dp501.c
@@ -224,8 +224,10 @@ static bool ast_launch_m68k(struct drm_device *dev)
ast_load_dp501_microcode(dev) < 0)
return false;

- fw_addr = (u8 *)ast->dp501_fw->data;
- len = ast->dp501_fw->size;
+ if (ast->dp501_fw) {
+ fw_addr = (u8 *)ast->dp501_fw->data;
+ len = ast->dp501_fw->size;
+ }
}
/* Get BootAddress */
ast_moutdwm(ast, 0x1e6e2000, 0x1688a8a8);
--
2.30.2