| Message ID | 20210930222704.2631604-2-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | Add __alloc_size() | expand |
On Thu, Sep 30, 2021 at 03:26:57PM -0700, Kees Cook wrote: > After adding __alloc_size attributes to the allocators, GCC 9.3 (but not > later) may incorrectly evaluate the arguments to check_copy_size(), > getting seemingly confused by the size being returned from array_size(). > Instead, perform the calculation once, which both makes the code more > readable and avoids the bug in GCC. > > In file included from arch/x86/include/asm/preempt.h:7, > from include/linux/preempt.h:78, > from include/linux/spinlock.h:55, > from include/linux/mm_types.h:9, > from include/linux/buildid.h:5, > from include/linux/module.h:14, > from drivers/rapidio/devices/rio_mport_cdev.c:13: > In function 'check_copy_size', > inlined from 'copy_from_user' at include/linux/uaccess.h:191:6, > inlined from 'rio_mport_transfer_ioctl' at drivers/rapidio/devices/rio_mport_cdev.c:983:6: > include/linux/thread_info.h:213:4: error: call to '__bad_copy_to' declared with attribute error: copy destination size is too small > 213 | __bad_copy_to(); > | ^~~~~~~~~~~~~~~ > > But the allocation size and the copy size are identical: > > transfer = vmalloc(array_size(sizeof(*transfer), transaction.count)); > if (!transfer) > return -ENOMEM; > > if (unlikely(copy_from_user(transfer, > (void __user *)(uintptr_t)transaction.block, > array_size(sizeof(*transfer), transaction.count)))) { > > Reported-by: kernel test robot <lkp@intel.com> > Link: https://lore.kernel.org/linux-mm/202109091134.FHnRmRxu-lkp@intel.com/ > Cc: Matt Porter <mporter@kernel.crashing.org> > Cc: Alexandre Bounine <alex.bou9@gmail.com> > Cc: Jing Xiangfeng <jingxiangfeng@huawei.com> > Cc: Ira Weiny <ira.weiny@intel.com> > Cc: Souptick Joarder <jrdr.linux@gmail.com> > Cc: Gustavo A. R. Silva <gustavoars@kernel.org> > Signed-off-by: Kees Cook <keescook@chromium.org> > Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Thanks -- Gustavo > --- > drivers/rapidio/devices/rio_mport_cdev.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c > index 94331d999d27..7df466e22282 100644 > --- a/drivers/rapidio/devices/rio_mport_cdev.c > +++ b/drivers/rapidio/devices/rio_mport_cdev.c > @@ -965,6 +965,7 @@ static int rio_mport_transfer_ioctl(struct file *filp, void __user *arg) > struct rio_transfer_io *transfer; > enum dma_data_direction dir; > int i, ret = 0; > + size_t size; > > if (unlikely(copy_from_user(&transaction, arg, sizeof(transaction)))) > return -EFAULT; > @@ -976,13 +977,14 @@ static int rio_mport_transfer_ioctl(struct file *filp, void __user *arg) > priv->md->properties.transfer_mode) == 0) > return -ENODEV; > > - transfer = vmalloc(array_size(sizeof(*transfer), transaction.count)); > + size = array_size(sizeof(*transfer), transaction.count); > + transfer = vmalloc(size); > if (!transfer) > return -ENOMEM; > > if (unlikely(copy_from_user(transfer, > (void __user *)(uintptr_t)transaction.block, > - array_size(sizeof(*transfer), transaction.count)))) { > + size))) { > ret = -EFAULT; > goto out_free; > } > @@ -994,8 +996,7 @@ static int rio_mport_transfer_ioctl(struct file *filp, void __user *arg) > transaction.sync, dir, &transfer[i]); > > if (unlikely(copy_to_user((void __user *)(uintptr_t)transaction.block, > - transfer, > - array_size(sizeof(*transfer), transaction.count)))) > + transfer, size))) > ret = -EFAULT; > > out_free: > -- > 2.30.2 >
diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c index 94331d999d27..7df466e22282 100644 --- a/drivers/rapidio/devices/rio_mport_cdev.c +++ b/drivers/rapidio/devices/rio_mport_cdev.c @@ -965,6 +965,7 @@ static int rio_mport_transfer_ioctl(struct file *filp, void __user *arg) struct rio_transfer_io *transfer; enum dma_data_direction dir; int i, ret = 0; + size_t size; if (unlikely(copy_from_user(&transaction, arg, sizeof(transaction)))) return -EFAULT; @@ -976,13 +977,14 @@ static int rio_mport_transfer_ioctl(struct file *filp, void __user *arg) priv->md->properties.transfer_mode) == 0) return -ENODEV; - transfer = vmalloc(array_size(sizeof(*transfer), transaction.count)); + size = array_size(sizeof(*transfer), transaction.count); + transfer = vmalloc(size); if (!transfer) return -ENOMEM; if (unlikely(copy_from_user(transfer, (void __user *)(uintptr_t)transaction.block, - array_size(sizeof(*transfer), transaction.count)))) { + size))) { ret = -EFAULT; goto out_free; } @@ -994,8 +996,7 @@ static int rio_mport_transfer_ioctl(struct file *filp, void __user *arg) transaction.sync, dir, &transfer[i]); if (unlikely(copy_to_user((void __user *)(uintptr_t)transaction.block, - transfer, - array_size(sizeof(*transfer), transaction.count)))) + transfer, size))) ret = -EFAULT; out_free:
After adding __alloc_size attributes to the allocators, GCC 9.3 (but not later) may incorrectly evaluate the arguments to check_copy_size(), getting seemingly confused by the size being returned from array_size(). Instead, perform the calculation once, which both makes the code more readable and avoids the bug in GCC. In file included from arch/x86/include/asm/preempt.h:7, from include/linux/preempt.h:78, from include/linux/spinlock.h:55, from include/linux/mm_types.h:9, from include/linux/buildid.h:5, from include/linux/module.h:14, from drivers/rapidio/devices/rio_mport_cdev.c:13: In function 'check_copy_size', inlined from 'copy_from_user' at include/linux/uaccess.h:191:6, inlined from 'rio_mport_transfer_ioctl' at drivers/rapidio/devices/rio_mport_cdev.c:983:6: include/linux/thread_info.h:213:4: error: call to '__bad_copy_to' declared with attribute error: copy destination size is too small 213 | __bad_copy_to(); | ^~~~~~~~~~~~~~~ But the allocation size and the copy size are identical: transfer = vmalloc(array_size(sizeof(*transfer), transaction.count)); if (!transfer) return -ENOMEM; if (unlikely(copy_from_user(transfer, (void __user *)(uintptr_t)transaction.block, array_size(sizeof(*transfer), transaction.count)))) { Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/linux-mm/202109091134.FHnRmRxu-lkp@intel.com/ Cc: Matt Porter <mporter@kernel.crashing.org> Cc: Alexandre Bounine <alex.bou9@gmail.com> Cc: Jing Xiangfeng <jingxiangfeng@huawei.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Souptick Joarder <jrdr.linux@gmail.com> Cc: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> --- drivers/rapidio/devices/rio_mport_cdev.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)