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mirror-linux/fs
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David Howells c0410adf3d
afs: Fix the locking used by afs_get_link() 
The afs filesystem in the kernel doesn't do locking correctly for symbolic
links.  There are a number of problems:

 (1) It doesn't do any locking around afs_read_single() to prevent races
     between multiple ->get_link() calls, thereby allowing the possibility
     of leaks.

 (2) It doesn't use RCU barriering when accessing the buffer pointers
     during RCU pathwalk.

 (3) It can race with another thread updating the contents of the symlink
     if a third party updated it on the server.

Fix this by the following means:

 (0) Move symlink handling into its own file as this makes it more
     complicated.

 (1) Take the validate_lock around afs_read_single() to prevent races
     between multiple ->get_link() calls.

 (2) Keep a separate copy of the symlink contents with an rcu_head.  This
     is always going to be a lot smaller than a page, so it can be
     kmalloc'd and save quite a bit of memory.  It also needs a refcount
     for non-RCU pathwalk.

 (3) Split the symlink read and write-to-cache routines in afs from those
     for directories.

 (4) Discard the I/O buffer as soon as the write-to-cache completes as this
     is a full page (plus a folio_queue).

 (5) If there's no cache, discard the I/O buffer immediately after reading
     and copying if there is no cache.

Fixes: eae9e78951 ("afs: Use netfslib for symlinks, allowing them to be cached")
Fixes: 6698c02d64 ("afs: Locally initialise the contents of a new symlink on creation")
Closes: https://sashiko.dev/#/patchset/20260326104544.509518-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-25-dhowells@redhat.com
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
 		2026-05-12 14:42:33 +02:00
..
9p netfs: Fix potential for tearing in ->remote_i_size and ->zero_point 2026-05-12 14:42:30 +02:00
adfs ARM development for 7.1-rc1 2026-04-25 07:44:26 -07:00
affs Fixing livelocks in shrink_dcache_tree() 2026-04-21 07:30:44 -07:00
afs afs: Fix the locking used by afs_get_link() 2026-05-12 14:42:33 +02:00
autofs vfs-7.1-rc1.misc 2026-04-13 14:20:11 -07:00
befs treewide: change inode->i_ino from unsigned long to u64 2026-03-06 14:31:28 +01:00
bfs vfs-7.1-rc1.bh.metadata 2026-04-13 12:46:42 -07:00
btrfs for-7.1-rc1-tag 2026-04-27 16:35:44 -07:00
cachefiles vfs-7.1-rc1.kino 2026-04-13 12:19:01 -07:00
ceph We have a series from Alex which extends CephFS client metrics with 2026-04-24 13:47:19 -07:00
coda coda cleanups and fixes 2026-04-21 14:03:10 -07:00
configfs Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
cramfs treewide: change inode->i_ino from unsigned long to u64 2026-03-06 14:31:28 +01:00
crypto fscrypt updates for 7.1 2026-04-13 17:29:12 -07:00
debugfs debugfs: fix placement of EXPORT_SYMBOL_GPL for debugfs_create_str() 2026-04-02 16:15:23 +02:00
devpts Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
dlm ipv6: convert CONFIG_IPV6 to built-in only and clean up Kconfigs 2026-03-29 11:21:22 -07:00
ecryptfs eCryptfs changes for 7.1-rc1 2026-04-20 10:54:17 -07:00
efivarfs efivarfs: use QSTR() in efivarfs_alloc_dentry 2026-04-28 12:30:59 +02:00
efs treewide: change inode->i_ino from unsigned long to u64 2026-03-06 14:31:28 +01:00
erofs Changes since the last update: 2026-04-21 11:16:04 -07:00
exfat Description for this pull request: 2026-04-13 16:57:31 -07:00
exportfs Fixing livelocks in shrink_dcache_tree() 2026-04-21 07:30:44 -07:00
ext2 \n 2026-04-15 19:22:16 -07:00
ext4 Various clean ups and bug fixes in ext4 for 7.1: 2026-04-17 17:08:31 -07:00
f2fs f2fs-for-7.1-rc1 2026-04-21 14:50:04 -07:00
fat vfs-7.1-rc1.bh.metadata 2026-04-13 12:46:42 -07:00
freevxfs treewide: change inode->i_ino from unsigned long to u64 2026-03-06 14:31:28 +01:00
fuse fuse: fix writeback array overflow when max_pages is one 2026-05-11 14:19:01 +02:00
gfs2 gfs2 changes 2026-04-15 19:12:04 -07:00
hfs vfs-7.1-rc1.misc 2026-04-13 14:20:11 -07:00
hfsplus hfs/hfsplus updates for v7.1 2026-04-13 16:50:38 -07:00
hostfs Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
hpfs treewide: change inode->i_ino from unsigned long to u64 2026-03-06 14:31:28 +01:00
hugetlbfs mm.git review status for linus..mm-stable 2026-04-15 12:59:16 -07:00
iomap fscrypt updates for 7.1 2026-04-13 17:29:12 -07:00
isofs isofs: use QSTR_LEN() in isofs_cmp 2026-04-20 17:27:28 +02:00
jbd2 Various clean ups and bug fixes in ext4 for 7.1: 2026-04-17 17:08:31 -07:00
jffs2 treewide: change inode->i_ino from unsigned long to u64 2026-03-06 14:31:28 +01:00
jfs fs: Fix return in jfs_mkdir and orangefs_mkdir 2026-05-11 14:19:01 +02:00
kernfs Driver core changes for 7.1-rc1 2026-04-13 19:03:11 -07:00
lockd NFSD 7.1 Release Notes 2026-04-20 10:44:02 -07:00
minix vfs-7.1-rc1.bh.metadata 2026-04-13 12:46:42 -07:00
netfs netfs, afs: Fix write skipping in dir/link writepages 2026-05-12 14:42:32 +02:00
nfs NFS client updates for Linux 7.1 2026-04-24 14:20:03 -07:00
nfs_common NFSD: Remove NFSERR_EAGAIN 2026-01-02 13:43:41 -05:00
nfsd NFSD 7.1 Release Notes 2026-04-20 10:44:02 -07:00
nilfs2 mm.git review status for linus..mm-stable 2026-04-15 12:59:16 -07:00
nls
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notify \n 2026-04-27 16:40:24 -07:00
ntfs ntfs: Use return instead of goto in ntfs_mapping_pairs_decompress() 2026-04-30 07:05:48 +09:00
ntfs3 Changes for 7.1-rc1 2026-04-20 10:59:47 -07:00
ocfs2 Fixing livelocks in shrink_dcache_tree() 2026-04-21 07:30:44 -07:00
omfs vfs-7.1-rc1.misc 2026-04-13 14:20:11 -07:00
openpromfs
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orangefs fs: Fix return in jfs_mkdir and orangefs_mkdir 2026-05-11 14:19:01 +02:00
overlayfs ovl: fix verity lazy-load guard broken by fsverity_active() semantic change 2026-05-06 08:37:30 -07:00
proc mm.git review status for linus..mm-nonmm-stable 2026-04-16 20:11:56 -07:00
pstore mm.git review status for linus..mm-stable 2026-04-15 12:59:16 -07:00
qnx4 vfs-7.1-rc1.bh.metadata 2026-04-13 12:46:42 -07:00
qnx6 vfs-7.1-rc1.bh.metadata 2026-04-13 12:46:42 -07:00
quota quota: Fix race of dquot_scan_active() with quota deactivation 2026-03-25 13:15:36 +01:00
ramfs folio_batch: rename pagevec.h to folio_batch.h 2026-04-05 13:53:07 -07:00
resctrl mm.git review status for linus..mm-stable 2026-04-15 12:59:16 -07:00
romfs mm.git review status for linus..mm-stable 2026-02-18 20:50:32 -08:00
smb netfs: Fix potential for tearing in ->remote_i_size and ->zero_point 2026-05-12 14:42:30 +02:00
squashfs Squashfs: check metadata block offset is within range 2026-02-24 11:13:27 -08:00
sysfs Driver core fixes for 7.1-rc1 2026-04-19 12:58:08 -07:00
tests fs/tests: exec: Remove bad test vector 2026-03-18 11:41:53 -07:00
tracefs tracefs fixes for v7.1: 2026-04-22 15:09:01 -07:00
ubifs mm.git review status for linus..mm-nonmm-stable 2026-04-16 20:11:56 -07:00
udf udf: reject descriptors with oversized CRC length 2026-04-22 17:14:48 +02:00
ufs vfs-7.1-rc1.bh.metadata 2026-04-13 12:46:42 -07:00
unicode Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
vboxsf Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
verity vfs-7.1-rc1.kino 2026-04-13 12:19:01 -07:00
xfs xfs: new code for Linux 7.1 2026-04-13 17:03:48 -07:00
zonefs mm.git review status for linus..mm-stable 2026-04-15 12:59:16 -07:00
Kconfig ntfs: add Kconfig and Makefile 2026-02-19 21:51:00 +09:00
Kconfig.binfmt
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Makefile ntfs: add Kconfig and Makefile 2026-02-19 21:51:00 +09:00
aio.c fs: aio: reject partial mremap to avoid Null-pointer-dereference error 2026-04-24 00:34:59 +02:00
anon_inodes.c
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attr.c fs: attr: fix comment formatting and spelling issues 2026-04-07 11:26:11 +02:00
backing-file.c lsm: add backing_file LSM hooks 2026-04-03 16:53:50 -04:00
bad_inode.c fs: refactor ->update_time handling 2026-01-12 14:01:32 +01:00
binfmt_elf.c mm: unexport vm_brk_flags() and eliminate vm_flags parameter 2026-04-05 13:53:39 -07:00
binfmt_elf_fdpic.c vfs-7.1-rc1.kino 2026-04-13 12:19:01 -07:00
binfmt_flat.c
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binfmt_misc.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
binfmt_script.c
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bpf_fs_kfuncs.c bpf: Remove redundant KF_TRUSTED_ARGS flag from all kfuncs 2026-01-02 12:04:28 -08:00
buffer.c vfs-7.1-rc1.fixes 2026-04-23 17:08:04 -07:00
char_dev.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
compat_binfmt_elf.c
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coredump.c vfs-7.1-rc1.misc 2026-04-13 14:20:11 -07:00
d_path.c dcache: permit dynamic_dname()s up to NAME_MAX 2026-04-07 12:32:22 +02:00
dax.c dax changes for 7.1 2026-04-21 14:12:01 -07:00
dcache.c Fixing livelocks in shrink_dcache_tree() 2026-04-21 07:30:44 -07:00
direct-io.c
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drop_caches.c
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eventfd.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
eventpoll.c eventpoll: drop vestigial epi->dying flag 2026-04-24 00:37:01 +02:00
exec.c exec: use strnlen() in __set_task_comm 2026-04-01 12:26:07 -07:00
fcntl.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
fhandle.c Convert more 'alloc_obj' cases to default GFP_KERNEL arguments 2026-02-21 20:03:00 -08:00
file.c vfs-7.1-rc1.misc 2026-04-13 14:20:11 -07:00
file_attr.c vfs-7.0-rc2.fixes 2026-02-25 10:34:23 -08:00
file_table.c lsm/stable-7.1 PR 20260410 2026-04-13 15:17:28 -07:00
filesystems.c sysfs(2): fs_index() argument is _not_ a pathname 2026-01-16 12:52:04 -05:00
fs-writeback.c vfs-7.1-rc1.fixes 2026-04-23 17:08:04 -07:00
fs_context.c vfs-7.1-rc1.misc 2026-04-13 14:20:11 -07:00
fs_dirent.c
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fs_parser.c fs: remove fsparam_path / fs_param_is_path 2026-02-19 14:34:26 +01:00
fs_pin.c
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fs_struct.c fs: add <linux/init_task.h> for 'init_fs' 2026-01-14 16:50:37 +01:00
fserror.c treewide: change inode->i_ino from unsigned long to u64 2026-03-06 14:31:28 +01:00
fsopen.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
init.c struct filename series 2026-02-09 16:58:28 -08:00
inode.c fs: fix forced iversion increment on lazytime timestamp updates 2026-05-11 15:32:12 +02:00
internal.h lsm/stable-7.1 PR 20260410 2026-04-13 15:17:28 -07:00
ioctl.c
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kernel_read_file.c
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libfs.c vfs-7.1-rc1.bh.metadata 2026-04-13 12:46:42 -07:00
locks.c NFSD 7.1 Release Notes 2026-04-20 10:44:02 -07:00
mbcache.c vfs-7.1-rc1.misc 2026-04-13 14:20:11 -07:00
mnt_idmapping.c fs/statmount: fix slab out-of-bounds write in statmount_mnt_idmap 2026-05-11 14:19:01 +02:00
mount.h fs: add immutable rootfs 2026-01-12 16:52:09 +01:00
mpage.c mm.git review status for linus..mm-stable 2026-04-15 12:59:16 -07:00
namei.c vfs-7.1-rc1.misc 2026-04-13 14:20:11 -07:00
namespace.c mount: always duplicate mount 2026-04-14 09:30:15 +02:00
nsfs.c nsfs: fix wrong error code returned for pidns ioctls 2026-05-11 15:59:14 +02:00
nullfs.c fs: add immutable rootfs 2026-01-12 16:52:09 +01:00
open.c fs: remove do_sys_truncate 2026-03-23 12:41:58 +01:00
pidfs.c vfs-7.1-rc1.pidfs 2026-04-13 13:27:11 -07:00
pipe.c treewide: change inode->i_ino from unsigned long to u64 2026-03-06 14:31:28 +01:00
pnode.c
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pnode.h
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posix_acl.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
proc_namespace.c
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read_write.c fs: add setlease to generic_ro_fops and read-only filesystem directory operations 2026-01-12 10:55:45 +01:00
readdir.c fs: Replace user_access_{begin/end} by scoped user access 2026-03-24 14:44:02 +01:00
remap_range.c
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select.c fs/select: reject negative timeval components in kern_select() 2026-05-12 14:41:40 +02:00
seq_file.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
signalfd.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
splice.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
stack.c
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stat.c statx: switch to CLASS(filename_maybe_null) 2026-01-16 12:52:04 -05:00
statfs.c user_statfs(): switch to CLASS(filename) 2026-01-16 12:52:04 -05:00
super.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
sync.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
sysctls.c
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timerfd.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
userfaultfd.c userfaultfd: allow registration of ranges below mmap_min_addr 2026-04-18 00:10:56 -07:00
utimes.c do_utimes_path(): switch to CLASS(filename_uflags) 2026-01-16 12:52:03 -05:00
xattr.c xattr: support extended attributes on sockets 2026-03-02 11:06:42 +01:00