[PATCH 0/5] mm: clarify nofail memory allocation

Barry Song
2024-07-24T08:56:07Z

From: Barry Song <v-songbaohua@oppo.com>

__GFP_NOFAIL carries the semantics of never failing, so its callers
do not check the return value:
%__GFP_NOFAIL: The VM implementation _must_ retry infinitely: the caller
cannot handle allocation failures. The allocation could block
indefinitely but will never return with failure. Testing for
failure is pointless.

However, __GFP_NOFAIL can sometimes fail if it exceeds size limits
or is used with GFP_ATOMIC/GFP_NOWAIT in a non-sleepable context.
This can expose security vulnerabilities due to potential NULL
dereferences.

Since __GFP_NOFAIL does not support non-blocking allocation, we introduce
GFP_NOFAIL with inclusive blocking semantics and encourage using GFP_NOFAIL
as a replacement for __GFP_NOFAIL in non-mm.

If we must still fail a nofail allocation, we should trigger a BUG rather
than exposing NULL dereferences to callers who do not check the return
value.

* The discussion started from this topic:
[PATCH RFC] mm: warn potential return NULL for kmalloc_array and
kvmalloc_array with __GFP_NOFAIL

https://lore.kernel.org/linux-mm/20240717230025.77361-1-21cnbao@gmail.com/

Thank you to Michal, Christoph, Vlastimil, and Hailong for all the
comments.

Barry Song (5):
vpda: try to fix the potential crash due to misusing __GFP_NOFAIL
mm: Document __GFP_NOFAIL must be blockable
mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails
mm: Introduce GFP_NOFAIL with the inclusion of __GFP_RECLAIM
non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

arch/powerpc/sysdev/xive/common.c | 2 +-
drivers/gpu/drm/drm_modeset_lock.c | 2 +-
drivers/gpu/drm/nouveau/nouveau_dmem.c | 8 +++----
drivers/gpu/drm/virtio/virtgpu_vq.c | 2 +-
drivers/hv/vmbus_drv.c | 2 +-
drivers/infiniband/hw/cxgb4/mem.c | 4 ++--
drivers/md/dm-region-hash.c | 2 +-
.../chelsio/inline_crypto/chtls/chtls_cm.c | 6 ++---
.../chelsio/inline_crypto/chtls/chtls_hw.c | 2 +-
drivers/target/iscsi/cxgbit/cxgbit_cm.c | 2 +-
drivers/tty/tty_ldisc.c | 2 +-
drivers/vdpa/vdpa_user/iova_domain.c | 24 +++++++++++++++----
fs/bcachefs/btree_iter.c | 2 +-
fs/bcachefs/fs-io-buffered.c | 2 +-
fs/bcachefs/io_write.c | 2 +-
fs/btrfs/extent_io.c | 8 +++----
fs/buffer.c | 6 ++---
fs/erofs/fscache.c | 2 +-
fs/erofs/zdata.c | 10 ++++----
fs/ext4/extents.c | 8 +++----
fs/ext4/extents_status.c | 4 ++--
fs/ext4/mballoc.c | 12 +++++-----
fs/ext4/page-io.c | 2 +-
fs/f2fs/checkpoint.c | 2 +-
fs/f2fs/data.c | 4 ++--
fs/f2fs/f2fs.h | 2 +-
fs/f2fs/node.c | 2 +-
fs/fuse/dev.c | 2 +-
fs/fuse/file.c | 4 ++--
fs/fuse/inode.c | 4 ++--
fs/fuse/virtio_fs.c | 4 ++--
fs/gfs2/meta_io.c | 2 +-
fs/gfs2/rgrp.c | 6 ++---
fs/gfs2/trans.c | 2 +-
fs/iomap/buffered-io.c | 2 +-
fs/jbd2/journal.c | 4 ++--
fs/jbd2/revoke.c | 2 +-
fs/jbd2/transaction.c | 6 ++---
fs/notify/fanotify/fanotify.c | 2 +-
fs/reiserfs/journal.c | 2 +-
fs/udf/directory.c | 2 +-
fs/xfs/libxfs/xfs_alloc.c | 2 +-
fs/xfs/libxfs/xfs_attr_leaf.c | 8 +++----
fs/xfs/libxfs/xfs_bmap.c | 2 +-
fs/xfs/libxfs/xfs_btree.h | 2 +-
fs/xfs/libxfs/xfs_btree_staging.c | 2 +-
fs/xfs/libxfs/xfs_da_btree.c | 8 +++----
fs/xfs/libxfs/xfs_defer.c | 4 ++--
fs/xfs/libxfs/xfs_dir2.c | 10 ++++----
fs/xfs/libxfs/xfs_dir2_block.c | 2 +-
fs/xfs/libxfs/xfs_dir2_sf.c | 8 +++----
fs/xfs/libxfs/xfs_exchmaps.c | 4 ++--
fs/xfs/libxfs/xfs_iext_tree.c | 4 ++--
fs/xfs/libxfs/xfs_inode_fork.c | 14 +++++------
fs/xfs/libxfs/xfs_refcount.c | 4 ++--
fs/xfs/libxfs/xfs_rmap.c | 2 +-
fs/xfs/xfs_attr_item.c | 8 +++----
fs/xfs/xfs_attr_list.c | 2 +-
fs/xfs/xfs_bmap_item.c | 6 ++---
fs/xfs/xfs_buf.c | 8 +++----
fs/xfs/xfs_buf_item.c | 4 ++--
fs/xfs/xfs_buf_item_recover.c | 2 +-
fs/xfs/xfs_dquot.c | 2 +-
fs/xfs/xfs_exchmaps_item.c | 4 ++--
fs/xfs/xfs_extent_busy.c | 2 +-
fs/xfs/xfs_extfree_item.c | 10 ++++----
fs/xfs/xfs_icache.c | 2 +-
fs/xfs/xfs_icreate_item.c | 2 +-
fs/xfs/xfs_inode_item.c | 2 +-
fs/xfs/xfs_inode_item_recover.c | 2 +-
fs/xfs/xfs_iunlink_item.c | 2 +-
fs/xfs/xfs_iwalk.c | 2 +-
fs/xfs/xfs_log.c | 2 +-
fs/xfs/xfs_log_cil.c | 2 +-
fs/xfs/xfs_log_recover.c | 6 ++---
fs/xfs/xfs_mount.c | 2 +-
fs/xfs/xfs_mru_cache.c | 4 ++--
fs/xfs/xfs_qm.c | 4 ++--
fs/xfs/xfs_refcount_item.c | 8 +++----
fs/xfs/xfs_rmap_item.c | 8 +++----
fs/xfs/xfs_rtalloc.c | 2 +-
fs/xfs/xfs_super.c | 2 +-
fs/xfs/xfs_trans.c | 4 ++--
fs/xfs/xfs_trans_dquot.c | 2 +-
include/linux/buffer_head.h | 4 ++--
include/linux/gfp_types.h | 7 ++++++
include/linux/slab.h | 4 +++-
kernel/resource.c | 2 +-
lib/list-test.c | 8 +++----
lib/ref_tracker.c | 2 +-
lib/rhashtable.c | 6 ++---
lib/test_hmm.c | 6 ++---
mm/page_alloc.c | 10 ++++----
mm/util.c | 1 +
net/ceph/osd_client.c | 2 +-
net/ceph/osdmap.c | 4 ++--
net/core/sock.c | 4 ++--
net/ipv4/inet_connection_sock.c | 2 +-
net/ipv4/tcp_output.c | 2 +-
security/smack/smackfs.c | 2 +-
100 files changed, 222 insertions(+), 196 deletions(-)

--
2.34.1