Message ID | 20231026021056.850680-1-suhui@nfschina.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | vga_switcheroo: Fix impossible judgment condition | expand |
On Thu, Oct 26, 2023 at 10:10:57AM +0800, Su Hui wrote: > 'id' is enum type like unsigned int, so it will never be less than zero. > > Fixes: 4aaf448fa975 ("vga_switcheroo: set audio client id according to bound GPU id") > Signed-off-by: Su Hui <suhui@nfschina.com> > --- > drivers/gpu/vga/vga_switcheroo.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c > index 365e6ddbe90f..d3064466fd3a 100644 > --- a/drivers/gpu/vga/vga_switcheroo.c > +++ b/drivers/gpu/vga/vga_switcheroo.c > @@ -375,7 +375,7 @@ int vga_switcheroo_register_audio_client(struct pci_dev *pdev, > mutex_lock(&vgasr_mutex); > if (vgasr_priv.active) { > id = vgasr_priv.handler->get_client_id(vga_dev); > - if (id < 0) { > + if ((int)id < 0) { Hi, I feel like you're using Smatch? Which is great! Fantastic! Have you built the cross function database? If you have there is a command that's useful. $ ~/smatch/smatch_db/smdb.py functions vga_switcheroo_handler get_client_id | tee where drivers/gpu/drm/nouveau/nouveau_acpi.c | (struct vga_switcheroo_handler)->get_client_id | nouveau_dsm_get_client_id | 1 drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c | (struct vga_switcheroo_handler)->get_client_id | amdgpu_atpx_get_client_id | 1 drivers/gpu/drm/radeon/radeon_atpx_handler.c | (struct vga_switcheroo_handler)->get_client_id | radeon_atpx_get_client_id | 1 drivers/platform/x86/apple-gmux.c | (struct vga_switcheroo_handler)->get_client_id | gmux_get_client_id | 1 $ make cscope $ vim where Use cscope to jump to each of those four functions. Move the cursor to the nouveau_dsm_get_client_id and hit CTRL-]. They never return negatives. The enum vga_switcheroo_client_id has a VGA_SWITCHEROO_UNKNOWN_ID define which I guess these functions are supposed to return on error. They never do return that, but I bet that's what we are supposed to check for. It honestly might be good to check for both... if ((int)id < 0 || id == VGA_SWITCHEROO_UNKNOWN_ID) { mutex_unlock(&vgasr_mutex); return -EINVAL; } regards, dan carpenter
On 2023/10/26 12:44, Dan Carpenter wrote: > On Thu, Oct 26, 2023 at 10:10:57AM +0800, Su Hui wrote: >> 'id' is enum type like unsigned int, so it will never be less than zero. >> >> Fixes: 4aaf448fa975 ("vga_switcheroo: set audio client id according to bound GPU id") >> Signed-off-by: Su Hui <suhui@nfschina.com> >> --- >> drivers/gpu/vga/vga_switcheroo.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c >> index 365e6ddbe90f..d3064466fd3a 100644 >> --- a/drivers/gpu/vga/vga_switcheroo.c >> +++ b/drivers/gpu/vga/vga_switcheroo.c >> @@ -375,7 +375,7 @@ int vga_switcheroo_register_audio_client(struct pci_dev *pdev, >> mutex_lock(&vgasr_mutex); >> if (vgasr_priv.active) { >> id = vgasr_priv.handler->get_client_id(vga_dev); >> - if (id < 0) { >> + if ((int)id < 0) { > Hi, > > I feel like you're using Smatch? Which is great! Fantastic! Yep, Smatch helps me a lot to find these bugs! I really like this excellent tool! > > Have you built the cross function database? If you have there is a > command that's useful. Not yet, bu I want to build this. > $ ~/smatch/smatch_db/smdb.py functions vga_switcheroo_handler get_client_id | tee where > drivers/gpu/drm/nouveau/nouveau_acpi.c | (struct vga_switcheroo_handler)->get_client_id | nouveau_dsm_get_client_id | 1 > drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c | (struct vga_switcheroo_handler)->get_client_id | amdgpu_atpx_get_client_id | 1 > drivers/gpu/drm/radeon/radeon_atpx_handler.c | (struct vga_switcheroo_handler)->get_client_id | radeon_atpx_get_client_id | 1 > drivers/platform/x86/apple-gmux.c | (struct vga_switcheroo_handler)->get_client_id | gmux_get_client_id | 1 > $ make cscope > $ vim where > Use cscope to jump to each of those four functions. Move the cursor to > the nouveau_dsm_get_client_id and hit CTRL-]. Sounds great! I must try this! > > They never return negatives. The enum vga_switcheroo_client_id has a > VGA_SWITCHEROO_UNKNOWN_ID define which I guess these functions are > supposed to return on error. They never do return that, but I bet > that's what we are supposed to check for. It honestly might be good > to check for both... > > if ((int)id < 0 || id == VGA_SWITCHEROO_UNKNOWN_ID) { > mutex_unlock(&vgasr_mutex); > return -EINVAL; > } Agreed, I will send v2 patch soon. Really thanks for your wonderful suggestion! :) Su Hui > regards, > dan carpenter >
On Thu, Oct 26, 2023 at 04:46:29PM +0800, Su Hui wrote: > On 2023/10/26 12:44, Dan Carpenter wrote: > > On Thu, Oct 26, 2023 at 10:10:57AM +0800, Su Hui wrote: > > > 'id' is enum type like unsigned int, so it will never be less than zero. > > > > > > Fixes: 4aaf448fa975 ("vga_switcheroo: set audio client id according to bound GPU id") > > > Signed-off-by: Su Hui <suhui@nfschina.com> > > > --- > > > drivers/gpu/vga/vga_switcheroo.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c > > > index 365e6ddbe90f..d3064466fd3a 100644 > > > --- a/drivers/gpu/vga/vga_switcheroo.c > > > +++ b/drivers/gpu/vga/vga_switcheroo.c > > > @@ -375,7 +375,7 @@ int vga_switcheroo_register_audio_client(struct pci_dev *pdev, > > > mutex_lock(&vgasr_mutex); > > > if (vgasr_priv.active) { > > > id = vgasr_priv.handler->get_client_id(vga_dev); > > > - if (id < 0) { > > > + if ((int)id < 0) { > > Hi, > > > > I feel like you're using Smatch? Which is great! Fantastic! > Yep, Smatch helps me a lot to find these bugs! I really like this excellent > tool! > > > > Have you built the cross function database? If you have there is a > > command that's useful. > Not yet, bu I want to build this. Yeah. It's super useful for kernel development. It helps to understand how functions are called and where variables are set etc. The smatch documentation is crap, I know. But I did write a short blog about the cross function DB. https://staticthinking.wordpress.com/2023/05/02/the-cross-function-db/ It's simple to build, but it takes a long time. Just run smatch_scripts/build_kernel_data.sh regards, dan carpenter
diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c index 365e6ddbe90f..d3064466fd3a 100644 --- a/drivers/gpu/vga/vga_switcheroo.c +++ b/drivers/gpu/vga/vga_switcheroo.c @@ -375,7 +375,7 @@ int vga_switcheroo_register_audio_client(struct pci_dev *pdev, mutex_lock(&vgasr_mutex); if (vgasr_priv.active) { id = vgasr_priv.handler->get_client_id(vga_dev); - if (id < 0) { + if ((int)id < 0) { mutex_unlock(&vgasr_mutex); return -EINVAL; }
'id' is enum type like unsigned int, so it will never be less than zero. Fixes: 4aaf448fa975 ("vga_switcheroo: set audio client id according to bound GPU id") Signed-off-by: Su Hui <suhui@nfschina.com> --- drivers/gpu/vga/vga_switcheroo.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)