| From cb69fc2510d86b451ff86112a78a3f62ebff283c Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 30 Aug 2022 15:34:50 +0800 |
| Subject: drm/bridge: megachips: Fix a null pointer dereference bug |
| |
| From: Zheyu Ma <zheyuma97@gmail.com> |
| |
| [ Upstream commit 1ff673333d46d2c1b053ebd0c1c7c7c79e36943e ] |
| |
| When removing the module we will get the following warning: |
| |
| [ 31.911505] i2c-core: driver [stdp2690-ge-b850v3-fw] unregistered |
| [ 31.912484] general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN PTI |
| [ 31.913338] KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] |
| [ 31.915280] RIP: 0010:drm_bridge_remove+0x97/0x130 |
| [ 31.921825] Call Trace: |
| [ 31.922533] stdp4028_ge_b850v3_fw_remove+0x34/0x60 [megachips_stdpxxxx_ge_b850v3_fw] |
| [ 31.923139] i2c_device_remove+0x181/0x1f0 |
| |
| The two bridges (stdp2690, stdp4028) do not probe at the same time, so |
| the driver does not call ge_b850v3_resgiter() when probing, causing the |
| driver to try to remove the object that has not been initialized. |
| |
| Fix this by checking whether both the bridges are probed. |
| |
| Fixes: 11632d4aa2b3 ("drm/bridge: megachips: Ensure both bridges are probed before registration") |
| Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> |
| Signed-off-by: Robert Foss <robert.foss@linaro.org> |
| Link: https://patchwork.freedesktop.org/patch/msgid/20220830073450.1897020-1-zheyuma97@gmail.com |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c | 4 +++- |
| 1 file changed, 3 insertions(+), 1 deletion(-) |
| |
| diff --git a/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c b/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c |
| index cce98bf2a4e7..72248a565579 100644 |
| --- a/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c |
| +++ b/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c |
| @@ -296,7 +296,9 @@ static void ge_b850v3_lvds_remove(void) |
| * This check is to avoid both the drivers |
| * removing the bridge in their remove() function |
| */ |
| - if (!ge_b850v3_lvds_ptr) |
| + if (!ge_b850v3_lvds_ptr || |
| + !ge_b850v3_lvds_ptr->stdp2690_i2c || |
| + !ge_b850v3_lvds_ptr->stdp4028_i2c) |
| goto out; |
| |
| drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge); |
| -- |
| 2.35.1 |
| |
