| Message ID | 1354810806-81681-1-git-send-email-tim.gardner@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Dec 6, 2012 at 4:20 PM, Tim Gardner <tim.gardner@canonical.com> wrote: > Memory for _manager is allocated using kzalloc() but the result is not checked. > > Free _manager on error lest memory become orphaned. > > I was led to scrutinize ttm_page_alloc_init() from a smatch warning: > > drivers/gpu/drm/ttm/ttm_page_alloc.c:799 ttm_page_alloc_init() error: potential null dereference '_manager'. (kzalloc returns null) > > Cc: David Airlie <airlied@linux.ie> > Cc: Dave Airlie <airlied@redhat.com> > Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> > Cc: Zhao Yakui <yakui.zhao@intel.com> > Cc: David Howells <dhowells@redhat.com> > Cc: dri-devel@lists.freedesktop.org > Cc: stable@vger.kernel.org # 3.5+ > Signed-off-by: Tim Gardner <tim.gardner@canonical.com> > --- > > This patch applies to stable 3.5 and newer. > > drivers/gpu/drm/ttm/ttm_page_alloc.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c > index bd2a3b4..2c73d0a 100644 > --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c > +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c > @@ -798,6 +798,10 @@ int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages) > pr_info("Initializing pool allocator\n"); > > _manager = kzalloc(sizeof(*_manager), GFP_KERNEL); > + if (!_manager) { > + pr_err("ttm: Could not allocate _manager.\n"); > + return -ENOMEM; > + } This is fine, > > ttm_page_pool_init_locked(&_manager->wc_pool, GFP_HIGHUSER, "wc"); > > @@ -817,6 +821,7 @@ int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages) > &glob->kobj, "pool"); > if (unlikely(ret != 0)) { > kobject_put(&_manager->kobj); > + kfree(_manager); > _manager = NULL; I don;t think this is, since the kobject_put shuold free it. Dave.
On 12/06/2012 03:46 PM, Dave Airlie wrote: >> >> ttm_page_pool_init_locked(&_manager->wc_pool, GFP_HIGHUSER, "wc"); >> >> @@ -817,6 +821,7 @@ int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages) >> &glob->kobj, "pool"); >> if (unlikely(ret != 0)) { >> kobject_put(&_manager->kobj); >> + kfree(_manager); >> _manager = NULL; > > I don;t think this is, since the kobject_put shuold free it. > kobject_put only frees memory referenced by kobj, but not the memory pointed at by _manager. rtg
On Fri, Dec 7, 2012 at 9:05 AM, Tim Gardner <tim.gardner@canonical.com> wrote: > On 12/06/2012 03:46 PM, Dave Airlie wrote: > >>> >>> ttm_page_pool_init_locked(&_manager->wc_pool, GFP_HIGHUSER, >>> "wc"); >>> >>> @@ -817,6 +821,7 @@ int ttm_page_alloc_init(struct ttm_mem_global *glob, >>> unsigned max_pages) >>> &glob->kobj, "pool"); >>> if (unlikely(ret != 0)) { >>> kobject_put(&_manager->kobj); >>> + kfree(_manager); >>> _manager = NULL; >> >> >> I don;t think this is, since the kobject_put shuold free it. >> > > kobject_put only frees memory referenced by kobj, but not the memory pointed > at by _manager. > The memory pointed at by _manager is the memory freed by the kobj if I read the code correctly. Dave.
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c index bd2a3b4..2c73d0a 100644 --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c @@ -798,6 +798,10 @@ int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages) pr_info("Initializing pool allocator\n"); _manager = kzalloc(sizeof(*_manager), GFP_KERNEL); + if (!_manager) { + pr_err("ttm: Could not allocate _manager.\n"); + return -ENOMEM; + } ttm_page_pool_init_locked(&_manager->wc_pool, GFP_HIGHUSER, "wc"); @@ -817,6 +821,7 @@ int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages) &glob->kobj, "pool"); if (unlikely(ret != 0)) { kobject_put(&_manager->kobj); + kfree(_manager); _manager = NULL; return ret; }
Memory for _manager is allocated using kzalloc() but the result is not checked. Free _manager on error lest memory become orphaned. I was led to scrutinize ttm_page_alloc_init() from a smatch warning: drivers/gpu/drm/ttm/ttm_page_alloc.c:799 ttm_page_alloc_init() error: potential null dereference '_manager'. (kzalloc returns null) Cc: David Airlie <airlied@linux.ie> Cc: Dave Airlie <airlied@redhat.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Zhao Yakui <yakui.zhao@intel.com> Cc: David Howells <dhowells@redhat.com> Cc: dri-devel@lists.freedesktop.org Cc: stable@vger.kernel.org # 3.5+ Signed-off-by: Tim Gardner <tim.gardner@canonical.com> --- This patch applies to stable 3.5 and newer. drivers/gpu/drm/ttm/ttm_page_alloc.c | 5 +++++ 1 file changed, 5 insertions(+)