kernel/linux.git/fs/netfs, branch v6.12.80

netfs: Fix kernel BUG in netfs_limit_iter() for ITER_KVEC iterators

2026-04-02T11:09:52+00:00

[ Upstream commit 67e467a11f62ff64ad219dc6aa5459e132c79d14 ] When a process crashes and the kernel writes a core dump to a 9P filesystem, __kernel_write() creates an ITER_KVEC iterator. This iterator reaches netfs_limit_iter() via netfs_unbuffered_write(), which only handles ITER_FOLIOQ, ITER_BVEC and ITER_XARRAY iterator types, hitting the BUG() for any other type. Fix this by adding netfs_limit_kvec() following the same pattern as netfs_limit_bvec(), since both kvec and bvec are simple segment arrays with pointer and length fields. Dispatch it from netfs_limit_iter() when the iterator type is ITER_KVEC. Fixes: cae932d3aee5 ("netfs: Add func to calculate pagecount/size-limited span of an iterator") Reported-by: syzbot+9c058f0d63475adc97fd@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9c058f0d63475adc97fd Tested-by: syzbot+9c058f0d63475adc97fd@syzkaller.appspotmail.com Signed-off-by: Deepanshu Kartikey Link: https://patch.msgid.link/20260307090041.359870-1-kartikey406@gmail.com Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

netfs: Prevent duplicate unlocking

2025-10-12T10:57:17+00:00

[ Upstream commit 66d938e89e940e512f4c3deac938ecef399c13f9 ] The filio lock has been released here, so there is no need to jump to error_folio_unlock to release it again. Reported-by: syzbot+b73c7d94a151e2ee1e9b@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b73c7d94a151e2ee1e9b Signed-off-by: Lizhi Xu Acked-by: David Howells Reviewed-by: Paulo Alcantara (Red Hat) Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

netfs: Fix unbuffered write error handling

2025-08-28T14:31:04+00:00

[ Upstream commit a3de58b12ce074ec05b8741fa28d62ccb1070468 ] If all the subrequests in an unbuffered write stream fail, the subrequest collector doesn't update the stream->transferred value and it retains its initial LONG_MAX value. Unfortunately, if all active streams fail, then we take the smallest value of { LONG_MAX, LONG_MAX, ... } as the value to set in wreq->transferred - which is then returned from ->write_iter(). LONG_MAX was chosen as the initial value so that all the streams can be quickly assessed by taking the smallest value of all stream->transferred - but this only works if we've set any of them. Fix this by adding a flag to indicate whether the value in stream->transferred is valid and checking that when we integrate the values. stream->transferred can then be initialised to zero. This was found by running the generic/750 xfstest against cifs with cache=none. It splices data to the target file. Once (if) it has used up all the available scratch space, the writes start failing with ENOSPC. This causes ->write_iter() to fail. However, it was returning wreq->transferred, i.e. LONG_MAX, rather than an error (because it thought the amount transferred was non-zero) and iter_file_splice_write() would then try to clean up that amount of pipe bufferage - leading to an oops when it overran. The kernel log showed: CIFS: VFS: Send error in write = -28 followed by: BUG: kernel NULL pointer dereference, address: 0000000000000008 with: RIP: 0010:iter_file_splice_write+0x3a4/0x520 do_splice+0x197/0x4e0 or: RIP: 0010:pipe_buf_release (include/linux/pipe_fs_i.h:282) iter_file_splice_write (fs/splice.c:755) Also put a warning check into splice to announce if ->write_iter() returned that it had written more than it was asked to. Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Reported-by: Xiaoli Feng Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220445 Signed-off-by: David Howells Link: https://lore.kernel.org/915443.1755207950@warthog.procyon.org.uk cc: Paulo Alcantara cc: Steve French cc: Shyam Prasad N cc: netfs@lists.linux.dev cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: stable@vger.kernel.org Signed-off-by: Christian Brauner [ Dropped read_collect.c hunk ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

netfs: Fix ref leak on inserted extra subreq in write retry

2025-07-17T16:37:16+00:00

[ Upstream commit 97d8e8e52cb8ab3d7675880a92626d9a4332f7a6 ] The write-retry algorithm will insert extra subrequests into the list if it can't get sufficient capacity to split the range that needs to be retried into the sequence of subrequests it currently has (for instance, if the cifs credit pool has fewer credits available than it did when the range was originally divided). However, the allocator furnishes each new subreq with 2 refs and then another is added for resubmission, causing one to be leaked. Fix this by replacing the ref-getting line with a neutral trace line. Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Signed-off-by: David Howells Link: https://lore.kernel.org/20250701163852.2171681-6-dhowells@redhat.com Tested-by: Steve French Reviewed-by: Paulo Alcantara cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

netfs: Fix oops in write-retry from mis-resetting the subreq iterator

2025-07-10T14:05:02+00:00

[ Upstream commit 4481f7f2b3df123ec77e828c849138f75cff2bf2 ] Fix the resetting of the subrequest iterator in netfs_retry_write_stream() to use the iterator-reset function as the iterator may have been shortened by a previous retry. In such a case, the amount of data to be written by the subrequest is not "subreq->len" but "subreq->len - subreq->transferred". Without this, KASAN may see an error in iov_iter_revert(): BUG: KASAN: slab-out-of-bounds in iov_iter_revert lib/iov_iter.c:633 [inline] BUG: KASAN: slab-out-of-bounds in iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611 Read of size 4 at addr ffff88802912a0b8 by task kworker/u32:7/1147 CPU: 1 UID: 0 PID: 1147 Comm: kworker/u32:7 Not tainted 6.15.0-rc6-syzkaller-00052-g9f35e33144ae #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: events_unbound netfs_write_collection_worker Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 iov_iter_revert lib/iov_iter.c:633 [inline] iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611 netfs_retry_write_stream fs/netfs/write_retry.c:44 [inline] netfs_retry_writes+0x166d/0x1a50 fs/netfs/write_retry.c:231 netfs_collect_write_results fs/netfs/write_collect.c:352 [inline] netfs_write_collection_worker+0x23fd/0x3830 fs/netfs/write_collect.c:374 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Fixes: cd0277ed0c18 ("netfs: Use new folio_queue data type and iterator instead of xarray iter") Reported-by: syzbot+25b83a6f2c702075fcbc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=25b83a6f2c702075fcbc Signed-off-by: David Howells Link: https://lore.kernel.org/20250519090707.2848510-2-dhowells@redhat.com Tested-by: syzbot+25b83a6f2c702075fcbc@syzkaller.appspotmail.com cc: Paulo Alcantara cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

netfs: Fix i_size updating

2025-07-10T14:04:52+00:00

[ Upstream commit 2e0658940d90a3dc130bb3b7f75bae9f4100e01f ] Fix the updating of i_size, particularly in regard to the completion of DIO writes and especially async DIO writes by using a lock. The bug is triggered occasionally by the generic/207 xfstest as it chucks a bunch of AIO DIO writes at the filesystem and then checks that fstat() returns a reasonable st_size as each completes. The problem is that netfs is trying to do "if new_size > inode->i_size, update inode->i_size" sort of thing but without a lock around it. This can be seen with cifs, but shouldn't be seen with kafs because kafs serialises modification ops on the client whereas cifs sends the requests to the server as they're generated and lets the server order them. Fixes: 153a9961b551 ("netfs: Implement unbuffered/DIO write support") Signed-off-by: David Howells Link: https://lore.kernel.org/20250701163852.2171681-11-dhowells@redhat.com Reviewed-by: Paulo Alcantara (Red Hat) cc: Steve French cc: Paulo Alcantara cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

netfs: Only create /proc/fs/netfs with CONFIG_PROC_FS

2025-05-02T05:59:26+00:00

[ Upstream commit 40cb48eba3b4b79e110c1a35d33a48cac54507a2 ] When testing a special config: CONFIG_NETFS_SUPPORTS=y CONFIG_PROC_FS=n The system crashes with something like: [ 3.766197] ------------[ cut here ]------------ [ 3.766484] kernel BUG at mm/mempool.c:560! [ 3.766789] Oops: invalid opcode: 0000 [#1] SMP NOPTI [ 3.767123] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Tainted: G W [ 3.767777] Tainted: [W]=WARN [ 3.767968] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), [ 3.768523] RIP: 0010:mempool_alloc_slab.cold+0x17/0x19 [ 3.768847] Code: 50 fe ff 58 5b 5d 41 5c 41 5d 41 5e 41 5f e9 93 95 13 00 [ 3.769977] RSP: 0018:ffffc90000013998 EFLAGS: 00010286 [ 3.770315] RAX: 000000000000002f RBX: ffff888100ba8640 RCX: 0000000000000000 [ 3.770749] RDX: 0000000000000000 RSI: 0000000000000003 RDI: 00000000ffffffff [ 3.771217] RBP: 0000000000092880 R08: 0000000000000000 R09: ffffc90000013828 [ 3.771664] R10: 0000000000000001 R11: 00000000ffffffea R12: 0000000000092cc0 [ 3.772117] R13: 0000000000000400 R14: ffff8881004b1620 R15: ffffea0004ef7e40 [ 3.772554] FS: 0000000000000000(0000) GS:ffff8881b5f3c000(0000) knlGS:0000000000000000 [ 3.773061] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 3.773443] CR2: ffffffff830901b4 CR3: 0000000004296001 CR4: 0000000000770ef0 [ 3.773884] PKRU: 55555554 [ 3.774058] Call Trace: [ 3.774232] [ 3.774371] mempool_alloc_noprof+0x6a/0x190 [ 3.774649] ? _printk+0x57/0x80 [ 3.774862] netfs_alloc_request+0x85/0x2ce [ 3.775147] netfs_readahead+0x28/0x170 [ 3.775395] read_pages+0x6c/0x350 [ 3.775623] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.775928] page_cache_ra_unbounded+0x1bd/0x2a0 [ 3.776247] filemap_get_pages+0x139/0x970 [ 3.776510] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.776820] filemap_read+0xf9/0x580 [ 3.777054] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.777368] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.777674] ? find_held_lock+0x32/0x90 [ 3.777929] ? netfs_start_io_read+0x19/0x70 [ 3.778221] ? netfs_start_io_read+0x19/0x70 [ 3.778489] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.778800] ? lock_acquired+0x1e6/0x450 [ 3.779054] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.779379] netfs_buffered_read_iter+0x57/0x80 [ 3.779670] __kernel_read+0x158/0x2c0 [ 3.779927] bprm_execve+0x300/0x7a0 [ 3.780185] kernel_execve+0x10c/0x140 [ 3.780423] ? __pfx_kernel_init+0x10/0x10 [ 3.780690] kernel_init+0xd5/0x150 [ 3.780910] ret_from_fork+0x2d/0x50 [ 3.781156] ? __pfx_kernel_init+0x10/0x10 [ 3.781414] ret_from_fork_asm+0x1a/0x30 [ 3.781677] [ 3.781823] Modules linked in: [ 3.782065] ---[ end trace 0000000000000000 ]--- This is caused by the following error path in netfs_init(): if (!proc_mkdir("fs/netfs", NULL)) goto error_proc; Fix this by adding ifdef in netfs_main(), so that /proc/fs/netfs is only created with CONFIG_PROC_FS. Signed-off-by: Song Liu Link: https://lore.kernel.org/20250409170015.2651829-1-song@kernel.org Acked-by: David Howells Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

netfs: Fix netfs_unbuffered_read() to return ssize_t rather than int

2025-04-10T12:39:31+00:00

[ Upstream commit 07c574eb53d4cc9aa7b985bc8bfcb302e5dc4694 ] Fix netfs_unbuffered_read() to return an ssize_t rather than an int as netfs_wait_for_read() returns ssize_t and this gets implicitly truncated. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20250314164201.1993231-5-dhowells@redhat.com Acked-by: "Paulo Alcantara (Red Hat)" cc: Jeff Layton cc: Viacheslav Dubeyko cc: Alex Markuze cc: Ilya Dryomov cc: ceph-devel@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

netfs: Call `invalidate_cache` only if implemented

2025-03-28T21:03:29+00:00

commit 344b7ef248f420ed4ba3a3539cb0a0fc18df9a6c upstream. Many filesystems such as NFS and Ceph do not implement the `invalidate_cache` method. On those filesystems, if writing to the cache (`NETFS_WRITE_TO_CACHE`) fails for some reason, the kernel crashes like this: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 0 P4D 0 Oops: Oops: 0010 [#1] SMP PTI CPU: 9 UID: 0 PID: 3380 Comm: kworker/u193:11 Not tainted 6.13.3-cm4all1-hp #437 Hardware name: HP ProLiant DL380 Gen9/ProLiant DL380 Gen9, BIOS P89 10/17/2018 Workqueue: events_unbound netfs_write_collection_worker RIP: 0010:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 0018:ffff9b86e2ca7dc0 EFLAGS: 00010202 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 7fffffffffffffff RDX: 0000000000000001 RSI: ffff89259d576a18 RDI: ffff89259d576900 RBP: ffff89259d5769b0 R08: ffff9b86e2ca7d28 R09: 0000000000000002 R10: ffff89258ceaca80 R11: 0000000000000001 R12: 0000000000000020 R13: ffff893d158b9338 R14: ffff89259d576900 R15: ffff89259d5769b0 FS: 0000000000000000(0000) GS:ffff893c9fa40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 000000054442e003 CR4: 00000000001706f0 Call Trace: ? __die+0x1f/0x60 ? page_fault_oops+0x15c/0x460 ? try_to_wake_up+0x2d2/0x530 ? exc_page_fault+0x5e/0x100 ? asm_exc_page_fault+0x22/0x30 netfs_write_collection_worker+0xe9f/0x12b0 ? xs_poll_check_readable+0x3f/0x80 ? xs_stream_data_receive_workfn+0x8d/0x110 process_one_work+0x134/0x2d0 worker_thread+0x299/0x3a0 ? __pfx_worker_thread+0x10/0x10 kthread+0xba/0xe0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x30/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 Modules linked in: CR2: 0000000000000000 This patch adds the missing `NULL` check. Fixes: 0e0f2dfe880f ("netfs: Dispatch write requests to process a writeback slice") Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Signed-off-by: Max Kellermann Signed-off-by: David Howells Link: https://lore.kernel.org/r/20250314164201.1993231-3-dhowells@redhat.com Acked-by: "Paulo Alcantara (Red Hat)" cc: netfs@lists.linux.dev cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: stable@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman

fs/netfs/read_collect: add to next->prev_donated

2025-03-22T19:54:28+00:00

If multiple subrequests donate data to the same "next" request (depending on the subrequest completion order), each of them would overwrite the `prev_donated` field, causing data corruption and a BUG() crash ("Can't donate prior to front"). Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading") Closes: https://lore.kernel.org/netfs/CAKPOu+_4mUwYgQtRTbXCmi+-k3PGvLysnPadkmHOyB7Gz0iSMA@mail.gmail.com/ Cc: stable@vger.kernel.org Signed-off-by: Max Kellermann Signed-off-by: David Howells Signed-off-by: Greg Kroah-Hartman