| Message ID | 20230610021200.377452-1-sukrut.bellary@linux.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | accel/qaic: Fix dereferencing freed memory | expand |
Am 10.06.23 um 04:12 schrieb Sukrut Bellary: > smatch warning: > drivers/accel/qaic/qaic_data.c:620 qaic_free_object() error: > dereferencing freed memory 'obj->import_attach' > > obj->import_attach is detached and freed using dma_buf_detach(). > But used after free to decrease the dmabuf ref count using > dma_buf_put(). > > Fixes: ff13be830333 ("accel/qaic: Add datapath") > Signed-off-by: Sukrut Bellary <sukrut.bellary@linux.com> > --- > drivers/accel/qaic/qaic_data.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c > index e42c1f9ffff8..7cba4d680ea8 100644 > --- a/drivers/accel/qaic/qaic_data.c > +++ b/drivers/accel/qaic/qaic_data.c > @@ -613,11 +613,13 @@ static int qaic_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struc > static void qaic_free_object(struct drm_gem_object *obj) > { > struct qaic_bo *bo = to_qaic_bo(obj); > + struct dma_buf *dmabuf; Maybe move that variable into the if. > > if (obj->import_attach) { > /* DMABUF/PRIME Path */ > + dmabuf = obj->import_attach->dmabuf; > dma_buf_detach(obj->import_attach->dmabuf, obj->import_attach); > - dma_buf_put(obj->import_attach->dmabuf); > + dma_buf_put(dmabuf); I strongly assume you are not using the GEM prime helpers for this? Christian. > } else { > /* Private buffer allocation path */ > qaic_free_sgt(bo->sgt);
On 6/10/2023 7:42 AM, Sukrut Bellary wrote: > smatch warning: > drivers/accel/qaic/qaic_data.c:620 qaic_free_object() error: > dereferencing freed memory 'obj->import_attach' > > obj->import_attach is detached and freed using dma_buf_detach(). > But used after free to decrease the dmabuf ref count using > dma_buf_put(). > > Fixes: ff13be830333 ("accel/qaic: Add datapath") > Signed-off-by: Sukrut Bellary <sukrut.bellary@linux.com> > --- > drivers/accel/qaic/qaic_data.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c > index e42c1f9ffff8..7cba4d680ea8 100644 > --- a/drivers/accel/qaic/qaic_data.c > +++ b/drivers/accel/qaic/qaic_data.c > @@ -613,11 +613,13 @@ static int qaic_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struc > static void qaic_free_object(struct drm_gem_object *obj) > { > struct qaic_bo *bo = to_qaic_bo(obj); > + struct dma_buf *dmabuf; > > if (obj->import_attach) { > /* DMABUF/PRIME Path */ > + dmabuf = obj->import_attach->dmabuf; > dma_buf_detach(obj->import_attach->dmabuf, obj->import_attach); > - dma_buf_put(obj->import_attach->dmabuf); > + dma_buf_put(dmabuf); > } else { > /* Private buffer allocation path */ > qaic_free_sgt(bo->sgt); Reviewed-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@quicinc.com>
On 6/12/2023 4:52 PM, Christian König wrote: > > > Am 10.06.23 um 04:12 schrieb Sukrut Bellary: >> smatch warning: >> drivers/accel/qaic/qaic_data.c:620 qaic_free_object() error: >> dereferencing freed memory 'obj->import_attach' >> >> obj->import_attach is detached and freed using dma_buf_detach(). >> But used after free to decrease the dmabuf ref count using >> dma_buf_put(). >> >> Fixes: ff13be830333 ("accel/qaic: Add datapath") >> Signed-off-by: Sukrut Bellary <sukrut.bellary@linux.com> >> --- >> drivers/accel/qaic/qaic_data.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/accel/qaic/qaic_data.c >> b/drivers/accel/qaic/qaic_data.c >> index e42c1f9ffff8..7cba4d680ea8 100644 >> --- a/drivers/accel/qaic/qaic_data.c >> +++ b/drivers/accel/qaic/qaic_data.c >> @@ -613,11 +613,13 @@ static int qaic_gem_object_mmap(struct >> drm_gem_object *obj, struct vm_area_struc >> static void qaic_free_object(struct drm_gem_object *obj) >> { >> struct qaic_bo *bo = to_qaic_bo(obj); >> + struct dma_buf *dmabuf; > > Maybe move that variable into the if. > >> if (obj->import_attach) { >> /* DMABUF/PRIME Path */ >> + dmabuf = obj->import_attach->dmabuf; >> dma_buf_detach(obj->import_attach->dmabuf, obj->import_attach); >> - dma_buf_put(obj->import_attach->dmabuf); >> + dma_buf_put(dmabuf); > > I strongly assume you are not using the GEM prime helpers for this? > > Christian. Driver uses drm_gem_prime_fd_to_handle() helper function but it also registers for ->gem_prime_import() which is internally called by drm_gem_prime_fd_to_handle(). All the operations done in gem_prime_import() are undone here. > >> } else { >> /* Private buffer allocation path */ >> qaic_free_sgt(bo->sgt); >
Am 12.06.23 um 15:03 schrieb Pranjal Ramajor Asha Kanojiya: > > > On 6/12/2023 4:52 PM, Christian König wrote: >> >> >> Am 10.06.23 um 04:12 schrieb Sukrut Bellary: >>> smatch warning: >>> drivers/accel/qaic/qaic_data.c:620 qaic_free_object() error: >>> dereferencing freed memory 'obj->import_attach' >>> >>> obj->import_attach is detached and freed using dma_buf_detach(). >>> But used after free to decrease the dmabuf ref count using >>> dma_buf_put(). >>> >>> Fixes: ff13be830333 ("accel/qaic: Add datapath") >>> Signed-off-by: Sukrut Bellary <sukrut.bellary@linux.com> >>> --- >>> drivers/accel/qaic/qaic_data.c | 4 +++- >>> 1 file changed, 3 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/accel/qaic/qaic_data.c >>> b/drivers/accel/qaic/qaic_data.c >>> index e42c1f9ffff8..7cba4d680ea8 100644 >>> --- a/drivers/accel/qaic/qaic_data.c >>> +++ b/drivers/accel/qaic/qaic_data.c >>> @@ -613,11 +613,13 @@ static int qaic_gem_object_mmap(struct >>> drm_gem_object *obj, struct vm_area_struc >>> static void qaic_free_object(struct drm_gem_object *obj) >>> { >>> struct qaic_bo *bo = to_qaic_bo(obj); >>> + struct dma_buf *dmabuf; >> >> Maybe move that variable into the if. >> >>> if (obj->import_attach) { >>> /* DMABUF/PRIME Path */ >>> + dmabuf = obj->import_attach->dmabuf; >>> dma_buf_detach(obj->import_attach->dmabuf, >>> obj->import_attach); >>> - dma_buf_put(obj->import_attach->dmabuf); >>> + dma_buf_put(dmabuf); >> >> I strongly assume you are not using the GEM prime helpers for this? >> >> Christian. > > Driver uses drm_gem_prime_fd_to_handle() helper function but it also > registers for ->gem_prime_import() which is internally called by > drm_gem_prime_fd_to_handle(). All the operations done in > gem_prime_import() are undone here. Then why don't you use drm_prime_gem_destroy() which is the cleanup helper for imports created by ->gem_prime_import() ? That looks pretty much identical to what you do here manually. Regards, Christian. > >> >>> } else { >>> /* Private buffer allocation path */ >>> qaic_free_sgt(bo->sgt); >>
On 6/12/2023 7:21 AM, Christian König wrote: > Am 12.06.23 um 15:03 schrieb Pranjal Ramajor Asha Kanojiya: >> >> >> On 6/12/2023 4:52 PM, Christian König wrote: >>> >>> >>> Am 10.06.23 um 04:12 schrieb Sukrut Bellary: >>>> smatch warning: >>>> drivers/accel/qaic/qaic_data.c:620 qaic_free_object() error: >>>> dereferencing freed memory 'obj->import_attach' >>>> >>>> obj->import_attach is detached and freed using dma_buf_detach(). >>>> But used after free to decrease the dmabuf ref count using >>>> dma_buf_put(). >>>> >>>> Fixes: ff13be830333 ("accel/qaic: Add datapath") >>>> Signed-off-by: Sukrut Bellary <sukrut.bellary@linux.com> >>>> --- >>>> drivers/accel/qaic/qaic_data.c | 4 +++- >>>> 1 file changed, 3 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/accel/qaic/qaic_data.c >>>> b/drivers/accel/qaic/qaic_data.c >>>> index e42c1f9ffff8..7cba4d680ea8 100644 >>>> --- a/drivers/accel/qaic/qaic_data.c >>>> +++ b/drivers/accel/qaic/qaic_data.c >>>> @@ -613,11 +613,13 @@ static int qaic_gem_object_mmap(struct >>>> drm_gem_object *obj, struct vm_area_struc >>>> static void qaic_free_object(struct drm_gem_object *obj) >>>> { >>>> struct qaic_bo *bo = to_qaic_bo(obj); >>>> + struct dma_buf *dmabuf; >>> >>> Maybe move that variable into the if. >>> >>>> if (obj->import_attach) { >>>> /* DMABUF/PRIME Path */ >>>> + dmabuf = obj->import_attach->dmabuf; >>>> dma_buf_detach(obj->import_attach->dmabuf, >>>> obj->import_attach); >>>> - dma_buf_put(obj->import_attach->dmabuf); >>>> + dma_buf_put(dmabuf); >>> >>> I strongly assume you are not using the GEM prime helpers for this? >>> >>> Christian. >> >> Driver uses drm_gem_prime_fd_to_handle() helper function but it also >> registers for ->gem_prime_import() which is internally called by >> drm_gem_prime_fd_to_handle(). All the operations done in >> gem_prime_import() are undone here. > > Then why don't you use drm_prime_gem_destroy() which is the cleanup > helper for imports created by ->gem_prime_import() ? > > That looks pretty much identical to what you do here manually. I think destroy() wasn't used because we are new to DRM and sometimes confused by the multitude of options. I appreciate the suggestion and will follow up to see if destroy() will work here, or identify what would prevent the use of it. -Jeff
On 6/12/2023 8:39 PM, Jeffrey Hugo wrote: > On 6/12/2023 7:21 AM, Christian König wrote: >> Am 12.06.23 um 15:03 schrieb Pranjal Ramajor Asha Kanojiya: >>> >>> >>> On 6/12/2023 4:52 PM, Christian König wrote: >>>> >>>> >>>> Am 10.06.23 um 04:12 schrieb Sukrut Bellary: >>>>> smatch warning: >>>>> drivers/accel/qaic/qaic_data.c:620 qaic_free_object() error: >>>>> dereferencing freed memory 'obj->import_attach' >>>>> >>>>> obj->import_attach is detached and freed using dma_buf_detach(). >>>>> But used after free to decrease the dmabuf ref count using >>>>> dma_buf_put(). >>>>> >>>>> Fixes: ff13be830333 ("accel/qaic: Add datapath") >>>>> Signed-off-by: Sukrut Bellary <sukrut.bellary@linux.com> >>>>> --- >>>>> drivers/accel/qaic/qaic_data.c | 4 +++- >>>>> 1 file changed, 3 insertions(+), 1 deletion(-) >>>>> >>>>> diff --git a/drivers/accel/qaic/qaic_data.c >>>>> b/drivers/accel/qaic/qaic_data.c >>>>> index e42c1f9ffff8..7cba4d680ea8 100644 >>>>> --- a/drivers/accel/qaic/qaic_data.c >>>>> +++ b/drivers/accel/qaic/qaic_data.c >>>>> @@ -613,11 +613,13 @@ static int qaic_gem_object_mmap(struct >>>>> drm_gem_object *obj, struct vm_area_struc >>>>> static void qaic_free_object(struct drm_gem_object *obj) >>>>> { >>>>> struct qaic_bo *bo = to_qaic_bo(obj); >>>>> + struct dma_buf *dmabuf; >>>> >>>> Maybe move that variable into the if. >>>> >>>>> if (obj->import_attach) { >>>>> /* DMABUF/PRIME Path */ >>>>> + dmabuf = obj->import_attach->dmabuf; >>>>> dma_buf_detach(obj->import_attach->dmabuf, >>>>> obj->import_attach); >>>>> - dma_buf_put(obj->import_attach->dmabuf); >>>>> + dma_buf_put(dmabuf); >>>> >>>> I strongly assume you are not using the GEM prime helpers for this? >>>> >>>> Christian. >>> >>> Driver uses drm_gem_prime_fd_to_handle() helper function but it also >>> registers for ->gem_prime_import() which is internally called by >>> drm_gem_prime_fd_to_handle(). All the operations done in >>> gem_prime_import() are undone here. >> >> Then why don't you use drm_prime_gem_destroy() which is the cleanup >> helper for imports created by ->gem_prime_import() ? >> >> That looks pretty much identical to what you do here manually. > > I think destroy() wasn't used because we are new to DRM and sometimes > confused by the multitude of options. I appreciate the suggestion and > will follow up to see if destroy() will work here, or identify what > would prevent the use of it. > > -Jeff Thank you Christian for your suggestion. I agree with you driver can use drm_prime_gem_destroy() here.
diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c index e42c1f9ffff8..7cba4d680ea8 100644 --- a/drivers/accel/qaic/qaic_data.c +++ b/drivers/accel/qaic/qaic_data.c @@ -613,11 +613,13 @@ static int qaic_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struc static void qaic_free_object(struct drm_gem_object *obj) { struct qaic_bo *bo = to_qaic_bo(obj); + struct dma_buf *dmabuf; if (obj->import_attach) { /* DMABUF/PRIME Path */ + dmabuf = obj->import_attach->dmabuf; dma_buf_detach(obj->import_attach->dmabuf, obj->import_attach); - dma_buf_put(obj->import_attach->dmabuf); + dma_buf_put(dmabuf); } else { /* Private buffer allocation path */ qaic_free_sgt(bo->sgt);
smatch warning: drivers/accel/qaic/qaic_data.c:620 qaic_free_object() error: dereferencing freed memory 'obj->import_attach' obj->import_attach is detached and freed using dma_buf_detach(). But used after free to decrease the dmabuf ref count using dma_buf_put(). Fixes: ff13be830333 ("accel/qaic: Add datapath") Signed-off-by: Sukrut Bellary <sukrut.bellary@linux.com> --- drivers/accel/qaic/qaic_data.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)