From 75da0eba0a47c4df45b3e214013ecc70f4586443 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 5 Nov 2021 13:36:15 -0700 Subject: [PATCH] rapidio: avoid bogus __alloc_size warning Patch series "Add __alloc_size()", v3. GCC and Clang both use the "alloc_size" attribute to assist with bounds checking around the use of allocation functions. Add the attribute, adjust the Makefile to silence needless warnings, and add the hints to the allocators where possible. These changes have been in use for a while now in GrapheneOS. This patch (of 8): 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)))) { Link: https://lkml.kernel.org/r/20210930222704.2631604-1-keescook@chromium.org Link: https://lkml.kernel.org/r/20210930222704.2631604-2-keescook@chromium.org Link: https://lore.kernel.org/linux-mm/202109091134.FHnRmRxu-lkp@intel.com/ Signed-off-by: Kees Cook Reviewed-by: John Hubbard Reported-by: kernel test robot Cc: Matt Porter Cc: Alexandre Bounine Cc: Jing Xiangfeng Cc: Ira Weiny Cc: Souptick Joarder Cc: Gustavo A. R. Silva Cc: Andy Whitcroft Cc: Christoph Lameter Cc: Daniel Micay Cc: David Rientjes Cc: Dennis Zhou Cc: Dwaipayan Ray Cc: Joe Perches Cc: Joonsoo Kim Cc: Lukas Bulwahn Cc: Miguel Ojeda Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Pekka Enberg Cc: Randy Dunlap Cc: Tejun Heo Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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: