bm_entry_read() allocates temporary buffer using __get_free_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-16-275e36a83f0e@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
configfs allocates staging buffers __get_free_pages().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_pages() with kzalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-15-275e36a83f0e@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
mnt_warn_timestamp_expiry() allocates memory for a path with
__get_free_page() although there is a dedicated helper for allocation of
file paths: __getname().
Replace __get_free_page() for allocation of a path buffer with __getname().
Christian Brauner <brauner@kernel.org> says:
Pass PATH_MAX (not PAGE_SIZE) to d_path() to match the size that
__getname() actually allocates, and drop the now-unnecessary NULL check
around __putname() since __putname() handles NULL. Both per Jan Kara's
review feedback, acked by the author.
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-14-275e36a83f0e@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
poll_get_entry() allocates new memory for poll_table entries using
__get_free_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-13-275e36a83f0e@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
fuse_do_ioctl allocates memory for struct iov array using
__get_free_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-12-275e36a83f0e@kernel.org
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
isofs_readdir() allocates a temporary buffer with __get_free_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-11-275e36a83f0e@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
jbd2_alloc() falls back from kmem_cache_alloc() to __get_free_pages() for
allocations larger than PAGE_SIZE.
But kmalloc() can handle such cases with essentially the same fallback.
Replace use of __get_free_pages() with kmalloc() and simplify
jbd2_free() as both kmem_cache_alloc() and kmalloc() allocations can be
freed with kfree().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-10-275e36a83f0e@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
jfs_readdir() allocates dirent_buf with __get_free_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-9-275e36a83f0e@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
simple_transaction_get() allocates memory with get_zeroed_page(). That
memory is used as a file local buffer that is accessed using
copy_from_user() and simple_read_from_buffer().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of get_zeroed_page() with kzalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-8-275e36a83f0e@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
nfsd_buffered_readdir() allocates a staging buffer with __get_free_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-7-275e36a83f0e@kernel.org
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Temporary buffers page and page2 allocated by nfs4_replace_transport() and
passed to nfs4_try_replacing_one_location() are never used.
Remove them and the code that allocates and frees memory for these buffers.
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-6-275e36a83f0e@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
nfs_show_devname() allocates a tmemporary buffer __get_free_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-5-275e36a83f0e@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
nilfs_ioctl_wrap_copy() allocates a temporary buffer with
get_zeroed_page().
kzalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of get_zeroed_page() with kzalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-4-275e36a83f0e@kernel.org
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
A few places in ocsfs2 allocate temporary buffers with __get_free_page() or
get_zeroed_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() and get_zeroed_page() with kmalloc() and
kzalloc() respectively.
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-3-275e36a83f0e@kernel.org
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
A few functions in fs/proc/base.c use __get_free_page() to allocate a
temporary buffer.
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-2-275e36a83f0e@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
dquot_init() allocates a single page for dquot_hash with
__get_free_pages().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_pages() with kmalloc() and get rid of the order
variable that remained 0 for more than 20 years.
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260523-b4-fs-v1-1-275e36a83f0e@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Agatha Isabelle Moreira <code@agatha.dev> says:
Refactor code to use `clear_and_wake_up_bit()` instead of manual calls
to:
clear_bit_unlock();
smp_mb__after_atomic();
wake_up_bit();
The helper function `clear_and_wake_up_bit()` was introduced in
'commit 8236b0ae31 ("bdi: wake up concurrent wb_shutdown()
callers.")' as a generic way of doing the same sequence of operations,
but several pieces of code still remain.
Replace manual calls to the operations by a single call to
`clear_and_wake_up_bit()` to deduplicate code and standardize pathways.
* patches from https://patch.msgid.link/ag4PEP52c8rxrYPc@guidai:
fs: jbd2: use clear_and_wake_up_bit() in journal_end_buffer_io_sync()
fs: buffer: use clear_and_wake_up_bit() in unlock_buffer()
Link: https://patch.msgid.link/ag4PEP52c8rxrYPc@guidai
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
initramfs_test_extract() and friends call unpack_to_rootfs() from a
kunit kthread while do_populate_rootfs() may still be running
asynchronously from rootfs_initcall. unpack_to_rootfs() keeps its
parser state in module-static variables (victim, byte_count, state,
this_header, header_buf, name_buf, ...), so the two writers corrupt
each other.
On arm64 v7.0-rc5+ this oopses early in boot:
Unable to handle kernel paging request at virtual address ffff80018f9f0ffc
pc : do_reset+0x3c/0x98
Call trace:
do_reset
initramfs_test_extract
kunit_try_run_case
Initramfs unpacking failed: junk within compressed archive
do_reset() faults because 'victim' was overwritten by the boot-time
unpacker; the boot unpacker meanwhile logs the bogus "junk within
compressed archive" on the real initrd because the test wrecked its
state machine.
Add a .suite_init callback that calls wait_for_initramfs() so the async
unpack is quiescent before the first case runs. suite_init runs once per
suite rather than before every individual test case.
Fixes: 83c0b27266 ("initramfs_test: kunit tests for initramfs unpacking")
Signed-off-by: Jia He <justin.he@arm.com>
Link: https://patch.msgid.link/20260519093937.1064628-1-justin.he@arm.com
Reviewed-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Use `clear_and_wake_up_bit()` in `journal_end_buffer_io_sync()`, since
the helper was introduced in 'commit 8236b0ae31 ("bdi: wake up
concurrent wb_shutdown() callers.")' as a generic way of doing the same
sequence of operations:
clear_bit_unlock();
smp_mb__after_atomic();
wake_up_bit();
The helper was first implemented to avoid bugs caused by forgetting to
call `wake_up_bit()` after `clear_bit_unlock()`.
Since `journal_end_buffer_io_sync()` was first introduced by 'commit
470decc613 ("jbd2: initial copy of files from jbd")' and last
modified in this operation by 'commit 4e857c58ef ("arch: Mass
conversion of smp_mb__*()")', years before `clear_and_wake_up_bit()`, it
still uses the open-coded sequence.
Replace the open-coded sequence with the helper to avoid duplicate code
and reduce code paths to maintain.
Suggested-by: shuo chen <1289151713@qq.com>
Link: https://lore.kernel.org/kernelnewbies/agzoqV835-co4kAN@guidai/T/#t
Signed-off-by: Agatha Isabelle Moreira <code@agatha.dev>
Link: https://patch.msgid.link/ag4SrrOl7R2DcLLi@guidai
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Use `clear_and_wake_up_bit()` in `unlock_buffer()`, since the helper was
introduced in 'commit 8236b0ae31 ("bdi: wake up concurrent
wb_shutdown() callers.")' as a generic way of doing the same sequence of
operations:
clear_bit_unlock();
smp_mb__after_atomic();
wake_up_bit();
The helper was implemented to avoid bugs caused by forgetting to call
`wake_up_bit()` after `clear_bit_unlock()`.
Since `unlock_buffer()` predates git and was last modified in
'commit 4e857c58ef ("arch: Mass conversion of smp_mb__*()")', years
before `clear_and_wake_up_bit()`, it still uses the open-coded sequence.
Replace the open-coded sequence with the helper to avoid duplicate code
and reduce code paths to maintain.
Suggested-by: shuo chen <1289151713@qq.com>
Link: https://lore.kernel.org/kernelnewbies/agzoqV835-co4kAN@guidai/T/#t
Signed-off-by: Agatha Isabelle Moreira <code@agatha.dev>
Link: https://patch.msgid.link/ag4SD-mkmn5IbuN7@guidai
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
At this point the superblock is already read, so jump to the label that
releases the buffer_head for it.
Fixes: d893fc670546 ("minix: handle set_blocksize failures")
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260518130330.529085-1-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Several places in init/do_mounts.c allocate temporary buffers for
filesystem names or options using __get_free_page() or alloc_page().
Usage of alloc_page() APIs is not required there and only creates
unnecessary noise with castings or conversion from struct page to void *.
kmalloc() is a better API for these uses and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() and alloc_page() with kmalloc().
While on it, add a check for -ENOMEM condition in mount_root_generic().
Link: https://lore.kernel.org/all/635405e4-9423-4a25-a6e7-e03c8ea0bcbe@redhat.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260520-init-v1-1-aaf2ebac5ad9@kernel.org
Reviewed-by: David Disseldorp <ddiss@suse.de>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Both GNU and BSD makes share a "token pipe" between their instances, as
a result a -j $BIGNUM invocation results in multicore perf problems in
the poll handler.
Avoiding the store will reduce it a little bit. However, the crux of the
problem is the locked queuing up in poll_wait().
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20260516021852.256932-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Symlinks can't appear as opened file.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Link: https://patch.msgid.link/295235c7-7f68-4554-bb6f-85398beca350@p183
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Drop the hard-coded length argument and use the simpler QSTR(). Inline
the code and drop the local variable.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://patch.msgid.link/20260505114242.158883-2-thorsten.blum@linux.dev
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Christoph Hellwig <hch@lst.de> says:
Due to an almost comical failure on my part, my work in progress test
case failed to create any file system on a 64k block size loop device,
and then tried to mount it, leading to a probe of file system built
into my kernel. Roughly the first half of the series are file systems
that actually crashed, but I fixed up all the pattern of missing
error handling that I saw.
* patches from https://patch.msgid.link/20260511071701.2456211-1-hch@lst.de:
omfs: handle set_blocksize failures
ntfs3: handle set_blocksize failures
minix: handle set_blocksize failures
isofs: handle set_blocksize failures
affs: handle set_blocksize failures
befs: handle set_blocksize failures
jfs: handle set_blocksize failures
qnx4: handle set_blocksize failures
hpfs: handle set_blocksize failures
bfs: handle set_blocksize failures
Link: https://patch.msgid.link/20260511071701.2456211-1-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
omfs uses buffer_heads, which don't handle block size > PAGE_SIZE well.
Without this, mounting we will hit the
BUG_ON(offset >= folio_size(folio));
in folio_set_bh on the first __bread_gfp call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260511071701.2456211-11-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
ntfs3 uses buffer_heads, which don't handle block size > PAGE_SIZE well.
Without this, mounting we will hit the
BUG_ON(offset >= folio_size(folio));
in folio_set_bh on the first __bread_gfp call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260511071701.2456211-10-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
minix uses buffer_heads, which don't handle block size > PAGE_SIZE well.
Without this, mounting we will hit the
BUG_ON(offset >= folio_size(folio));
in folio_set_bh on the first __bread_gfp call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260511071701.2456211-9-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
isofs uses buffer_heads, which don't handle block size > PAGE_SIZE well.
Without this, mounting we will hit the
BUG_ON(offset >= folio_size(folio));
in folio_set_bh on the first __bread_gfp call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260511071701.2456211-8-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
affs uses buffer_heads, which don't handle block size > PAGE_SIZE well.
Without this, mounting we will hit the
BUG_ON(offset >= folio_size(folio));
in folio_set_bh on the first __bread_gfp call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260511071701.2456211-7-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
befs uses buffer_heads, which don't handle block size > PAGE_SIZE well.
Without this, mounting we will hit the
BUG_ON(offset >= folio_size(folio));
in folio_set_bh on the first __bread_gfp call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260511071701.2456211-6-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
jfs uses buffer_heads, which don't handle block size > PAGE_SIZE well.
Without this, mounting we will hit the
BUG_ON(offset >= folio_size(folio));
in folio_set_bh on the first __bread_gfp call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260511071701.2456211-5-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
qnx4 uses buffer_heads, which don't handle block size > PAGE_SIZE well.
Without this, mounting will hit the
BUG_ON(offset >= folio_size(folio));
in folio_set_bh on the first __bread_gfp call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260511071701.2456211-4-hch@lst.de
Acked-by: Anders Larsen <al@alarsen.net>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
hpfs uses buffer_heads, which don't handle block size > PAGE_SIZE well.
Without this, mounting will hit the
BUG_ON(offset >= folio_size(folio));
in folio_set_bh on the first __bread_gfp call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260511071701.2456211-3-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
bfs uses buffer_heads, which don't handle block size > PAGE_SIZE well.
Without this, mounting will hit the
BUG_ON(offset >= folio_size(folio));
in folio_set_bh on the first __bread_gfp call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260511071701.2456211-2-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
This document is motivated by the ongoing maintenance burden that
abandoned and untestable filesystems impose on VFS developers, blocking
infrastructure changes such as folio conversions and iomap migration.
This week alone, two new filesystems were proposed on linux-fsdevel
(VMUFAT and FTRFS), highlighting the need for documented guidelines
that new filesystem authors can refer to before submission.
Multiple recent discussions on linux-fsdevel have touched on the
criteria for merging new filesystems and for deprecating old ones,
covering topics such as modern VFS interface adoption, testability,
userspace utilities, maintainer commitment, and user base viability.
Add Documentation/filesystems/adding-new-filesystems.rst describing
the technical requirements and community expectations for merging a
new filesystem into the kernel. The guidelines cover:
- Alternatives to consider before proposing a new in-kernel filesystem
- Technical requirements: modern VFS interfaces (iomap, folios,
fs_context mount API), testability, and userspace utilities
- Community expectations: identified maintainers, demonstrated
commitment, sustained backing, and a clear user base
- Ongoing obligations after merging, including the risk of deprecation
for unmaintained filesystems
Link: https://lore.kernel.org/linux-fsdevel/20260411151155.321214-1-adrianmcmenamin@gmail.com/
Link: https://lore.kernel.org/linux-fsdevel/20260413142357.515792-1-aurelien@hackers.camp/
Link: https://lore.kernel.org/linux-fsdevel/yndtg2jbj55fzd2kkhsmel4pp5ll5xfvfiaqh24tdct3jiqosd@jzbfzf3rrxrd/
Link: https://lore.kernel.org/linux-fsdevel/20260124091742.GA43313@macsyma.local/
Link: https://lore.kernel.org/lkml/20260111140345.3866-1-linkinjeon@kernel.org/
Cc: Christian Brauner <brauner@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jan Kara <jack@suse.cz>
Cc: Theodore Tso <tytso@mit.edu>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Assisted-by: Cursor:claude-4-opus
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://patch.msgid.link/20260422125212.1743006-1-amir73il@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
If d_flags isn't what we expect, then it's good to display it. Add a new
DENTRY_WARN_ONCE() macro that also displays d_flags for the dentry.
Change D_FLAG_VERIFY() to call that instead of a generic WARN_ON_ONCE().
Change the existing hlist_unhashed() check in dentry_free() to use the
new macro, and add checks for other invariants of a dead dentry. Notably:
1) Ensure that DCACHE_LRU_LIST and DCACHE_SHRINK_LIST are not set.
2) Ensure that d_lockref is negative
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260422-dcache-warn-v1-1-50155e1b40b6@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Currently, writing to 'core_pattern' or 'suid_dumpable' sysctl nodes
always triggers validate_coredump_safety(), even if the values have
not changed. This results in redundant warning messages in dmesg:
"Unsafe core_pattern used with fs.suid_dumpable=2..."
This patch optimizes the procfs handlers to only invoke the safety
validation when an actual change in the configuration is detected:
1. In proc_dostring_coredump(), compare the new core_pattern string
with the existing one using strncmp().
2. In proc_dointvec_minmax_coredump(), check if the new suid_dumpable
value differs from the previous one.
This keeps the kernel log clean from repetitive warnings when
re-applying the same sysctl settings.
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Link: https://patch.msgid.link/20260410080918.2319-1-lirongqing@baidu.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Use kmalloc_flex() when allocating a new 'struct external_name' in
__d_alloc() to replace offsetof() and the open-coded size arithmetic,
and to keep the size type-safe.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://patch.msgid.link/20260417094238.551114-3-thorsten.blum@linux.dev
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jori Koolstra <jkoolstra@xs4all.nl>
Signed-off-by: Christian Brauner <brauner@kernel.org>
find_next_fd() finds the next free fd slot in the passed fdtable's
bitmap. It does so in two steps: first it checks whether the bitmap
has a free entry in the word containing start. If not, it looks at
second level bitmap that registers which words in the first level bitmap
are full and then looks at the first level bitmap at the first non-full
word.
In the current code the second level lookup is done by:
bitbit = find_next_zero_bit(fdt->full_fds_bits, maxbit, bitbit) *
BITS_PER_LONG;
where bitbit = start / BITS_PER_LONG. However, in the fast path (first
step) we already checked the word at bitbit, so we can skip that word bit
and start at bitbit+1. This also means that we can get rid of the branch
if (bitbit > start)
start = bitbit;
since if we set
bitbit = find_next_zero_bit(fdt->full_fds_bits, maxbit, bitbit+1) *
BITS_PER_LONG;
the reassigned bitbit can never be less than
((start/BITS_PER_LONG)+1) * BITS_PER_LONG > start
So the branch is always taken.
Obviously the reuse of the variable name bitbit (and the name itself) is
quite confusing, so change that as well.
Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
Link: https://patch.msgid.link/20260420101801.806785-1-jkoolstra@xs4all.nl
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
While auditing the Linux 7.0-rc2 kernel, I identified a potential security
vulnerability in the iov_iter framework's memory allocation logic.
The dup_iter() function, which is exported via EXPORT_SYMBOL, currently
uses kmemdup() with a raw multiplication to allocate the duplicate iovec array:
new->iov = kmemdup(from->iov, nr_segs * sizeof(struct iovec), gfp);
The hazard here is that dup_iter() relies on a primitive multiplication without
any integrated overflow check. Since nr_segs is often derived from user-space
input, this line is vulnerable to integer overflow (on 32-bit systems or
via type narrowing), potentially leading to a small allocation followed by a
large out-of-bounds memory copy. Furthermore, it allows for unbounded memory
allocations, as the function lacks intrinsic knowledge of safe limits.
On the 7.0-rc2 branch, several high-impact callchains still rely on this
exported function:
drivers/usb/gadget/function/f_fs.c:
The ffs_epfile_read_iter() path demonstrates why relying on dup_iter() is
dangerous: it performs allocation based on user input before verifying driver
state. This confirms that dup_iter() must be hardened internally as it cannot
assume pre-validated input.
drivers/usb/gadget/legacy/inode.c:
The ep_read_iter() path illustrates how dup_iter()’s lack of boundary awareness
compounds resource risks. When combined with other allocations, it creates
a multiplier effect for kernel memory pressure.
This patch replaces kmemdup() with kmemdup_array(), which utilizes
check_mul_overflow() to ensure the allocation size is calculated safely,
hardening dup_iter() against malicious or malformed inputs from its callers
Signed-off-by: Wang Haoran <haoranwangsec@gmail.com>
Link: https://patch.msgid.link/20260413060655.1139141-1-haoranwangsec@gmail.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
David Disseldorp <ddiss@suse.de> says:
The series that introduced simple_strntoul() had passed into kernel
without proper review and hence reinvented a wheel that's not needed.
Here is the refactoring to show that. It can go via PRINTK or VFS
tree.
I have tested this on x86, but I believe the same result will be
on big-endian CPUs (I deduced that from how strtox() works).
I also run KUnit tests.
* patches from https://patch.msgid.link/20260331070519.5974-1-ddiss@suse.de:
kstrtox: Drop extern keyword in the simple_strtox() declarations
vsprintf: Revert "add simple_strntoul"
initramfs: Refactor to use hex2bin() instead of custom approach
initramfs: Sort headers alphabetically
initramfs_test: test header fields with 0x hex prefix
initramfs_test: add fill_cpio() inject_ox parameter
Link: https://patch.msgid.link/20260331070519.5974-1-ddiss@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
There is legacy 'extern' keyword for the exported simple_strtox()
function which are the artefact that can be removed. So drop it.
While at it, tweak the declaration to provide parameter names.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260331070519.5974-7-ddiss@suse.de
Reviewed-by: David Disseldorp <ddiss@suse.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
No users anymore and none should be in the first place.
This reverts commit fcc155008a.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260331070519.5974-6-ddiss@suse.de
Acked-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
There is a simple_strntoul() function used solely as a shortcut
for hex2bin() with proper endianess conversions. Replace that
and drop the unneeded function in the next changes.
This implementation will abort if we fail to parse the cpio header,
instead of using potentially bogus header values.
Co-developed-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260331070519.5974-5-ddiss@suse.de
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
