kernel/linux.git/fs/ceph, branch v7.1.12

ceph: fix hanging __ceph_get_caps() with stale mds_wanted

2026-08-23T12:29:28+00:00

[ Upstream commit 50958bb928bad3bdba9e5d1b7ff4bbadcf6951e6 ] A reader can hang forever in __ceph_get_caps() when the client no longer holds `FILE_RD`, but local cap state still says that the capability is already wanted (via `mds_wanted`). One way to trigger this is through MDS cap revocation. If another client performs a conflicting operation, the MDS can revoke `FILE_RD` from the reader; the next read then has to reacquire `FILE_RD`. If the cap update that should request `FILE_RD` never reaches the MDS after `cap->mds_wanted` was raised, the reader is left holding only non-file caps while local `mds_wanted` still includes the file read caps. In that state, try_get_cap_refs() sees `need <= mds_wanted` and returns 0, so __ceph_get_caps() just waits on `i_cap_wq`. If the cap update that was supposed to request `FILE_RD never reaches the MDS after `cap->mds_wanted was` raised, no further request is sent and the waiter can sleep indefinitely until unrelated cap traffic happens to wake it up. The ordering issue is that `cap->mds_wanted` is updated in __prep_cap() before the `CEPH_MSG_CLIENT_CAPS message` is actually queued for send. That makes one field serve two different meanings at once: what this client wants, and what the client believes the MDS already knows it wants. A proper fix would be to split those states and track whether a cap update is actually in flight or has been observed by the MDS. However, simply moving the `cap->mds_wanted assignment` later would not be sufficient: queueing the message in the messenger does not guarantee that the MDS processed that specific wanted set, and reconnect or message loss can still invalidate that assumption. Fixing that properly would require a larger rework of the cap state machine. To allow simpler backports to stable kernels, this patch implements a simpler workaround: - stop waiting forever in __ceph_get_caps(); after a bounded wait, fall back to the renew path - make ceph_renew_caps() issue a synchronous `OPEN` request whenever the inode still does not actually hold the wanted caps, instead of only calling ceph_check_caps() The extra issued-vs-wanted check in ceph_renew_caps() is necessary because the previous test only checked whether the inode still had any real caps at all. That is not enough after revocation: the client can still hold something like `pLs` and yet be missing `FILE_RD` completely. In that case, falling back to ceph_check_caps() is not sufficient, because it still trusts `cap->mds_wanted` and may resend nothing. By requiring `(issued & wanted) == wanted` before taking the asynchronous path, the code only uses ceph_check_caps() when the `wanted caps` are already actually issued. Otherwise, it sends the synchronous `OPEN` renew. This preserves the existing asynchronous fast path when the wanted caps are already issued, avoids changing cap-state semantics, and fixes the hang by guaranteeing that a stalled waiter eventually retries through a path that does not rely on the stale `mds_wanted` state. [ idryomov: move CEPH_GET_CAPS_WAIT_TIMEOUT from libceph.h to mds_client.h, formatting ] Cc: stable@vger.kernel.org Fixes: 0a454bdd501a ("ceph: reorganize __send_cap for less spinlock abuse") Signed-off-by: Max Kellermann Reviewed-by: Alex Markuze Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ceph: avoid fs reclaim while using current->journal_info

2026-08-23T12:29:28+00:00

[ Upstream commit 5b602344a49e039e792ce5a8923bcc61412ee134 ] handle_reply() stores a `ceph_mds_request` pointer in `current->journal_info` while filling the inode and dentry cache from an MDS reply. An allocation in this section can enter direct reclaim and prune dentries from another filesystem. If this dirties an ext4 inode, ext4 starts a JBD2 transaction. JBD2 interprets the Ceph request in `current->journal_info` as a journal handle and dereferences the request's `r_tid` as `h_transaction`, causing a kernel crash, e.g.: Unable to handle kernel paging request at virtual address 00000000077b4818 [...] Internal error: Oops: 0000000096000004 [#1] SMP Modules linked in: CPU: 6 UID: 0 PID: 2699135 Comm: kworker/6:3 Tainted: G W 6.18.38-i3 #1113 NONE [...] Workqueue: ceph-msgr ceph_con_workfn pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : jbd2__journal_start+0x2c/0x208 lr : __ext4_journal_start_sb+0x100/0x178 [...] Call trace: jbd2__journal_start+0x2c/0x208 (P) __ext4_journal_start_sb+0x100/0x178 ext4_dirty_inode+0x3c/0x90 __mark_inode_dirty+0x58/0x400 iput.part.0+0x2b0/0x370 iput+0x18/0x30 dentry_unlink_inode+0xc0/0x158 __dentry_kill+0x80/0x250 shrink_dentry_list+0x90/0x130 prune_dcache_sb+0x60/0x98 super_cache_scan+0xe8/0x190 do_shrink_slab+0x174/0x388 shrink_slab+0xd8/0x4c0 shrink_node+0x31c/0x908 do_try_to_free_pages+0xd0/0x508 try_to_free_pages+0x11c/0x238 __alloc_frozen_pages_noprof+0x4d0/0xdd0 __folio_alloc_noprof+0x18/0x70 __filemap_get_folio+0x248/0x440 ceph_readdir_prepopulate+0x570/0x9e8 mds_dispatch+0x1424/0x1ba0 ceph_con_process_message+0x74/0xa0 ceph_con_v1_try_read+0x3a0/0x1510 ceph_con_workfn+0x260/0x460 Enter a scoped NOFS allocation context and leave it after clearing `journal_info`. This prevents filesystem reclaim from recursing into another filesystem while the field contains Ceph-private data. Cc: stable@vger.kernel.org Fixes: 315f24088048 ("ceph: fix security xattr deadlock") Signed-off-by: Max Kellermann Reviewed-by: Viacheslav Dubeyko Reviewed-by: Xiubo Li Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ceph: fix MDS random selection readiness predicate

2026-08-23T12:29:22+00:00

commit 2c11c4bfdb7bd2808b3b3ac228e1f2d9bcf25457 upstream. CEPH_MDS_IS_READY() is parsed so that the ternary expression can return true for an MDS entry with state 0 when it is not laggy. This allows the random selector to choose a down/DNE rank. Group the ternary expression under the state check so zero-state ranks are not treated as ready. Cc: stable@vger.kernel.org Fixes: b38c9eb4757d ("ceph: add possible_max_rank and make the code more readable") Link: https://tracker.ceph.com/issues/78648 Signed-off-by: Yiming Zhu Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

ceph: fix writeback_count leak in write_folio_nounlock()

2026-08-03T09:25:56+00:00

commit cbf59617cd715219e84c50d106a3d0e1e8ba054e upstream. write_folio_nounlock() increments fsc->writeback_count to track in-flight writeback operations. On several error paths where the function returns early (folio lookup failure, snapshot context allocation failure, and writepages submission failure), the function returns without calling atomic_long_dec_return() to decrement the counter. Each leaked increment keeps the counter above zero, which can prevent the filesystem from cleanly unmounting or suspending writes. Add atomic_long_dec_return() calls on all error paths that currently return without decrementing the counter. Cc: stable@vger.kernel.org Fixes: d55207717ded ("ceph: add encryption support to writepage and writepages") Signed-off-by: Wentao Liang Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

ceph: fix refcount leak in ceph_readdir()

2026-08-03T09:25:55+00:00

commit c3e64079d8b9663e3998d0caac9aba915b6b93ae upstream. The ceph_readdir() function allocates a ceph_mds_request via ceph_mdsc_create_request() and stores it in dfi->last_readdir. In the directory entry processing loop, if the entry's offset is less than ctx->pos or if the inode pointer is unexpectedly NULL, the function returns -EIO without releasing the reference held by dfi->last_readdir, causing a refcount leak. Fix this by adding ceph_mdsc_put_request(dfi->last_readdir) before returning on these error paths. Also set dfi->last_readdir to NULL for safety, matching the cleanup done at the normal exit. Cc: stable@vger.kernel.org Fixes: af9ffa6df7e3 ("ceph: add support to readdir for encrypted names") Signed-off-by: WenTao Liang Reviewed-by: Viacheslav Dubeyko Reviewed-by: Alex Markuze Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

ceph: fix pre-auth out-of-bounds read on snaptrace in ceph_handle_caps()

2026-08-03T09:25:55+00:00

commit 4dbc71bcaf9a30abf3920a4e2cc4ed33bba78c02 upstream. ceph_handle_caps() reads snap_trace_len from the wire-format ceph_mds_caps header and uses it unconditionally to build a fake end pointer (snaptrace + snaptrace_len) that is later handed to ceph_update_snap_trace() in the CEPH_CAP_OP_IMPORT case: snaptrace = h + 1; snaptrace_len = le32_to_cpu(h->snap_trace_len); p = snaptrace + snaptrace_len; ... case CEPH_CAP_OP_IMPORT: if (snaptrace_len) { ... if (ceph_update_snap_trace(mdsc, snaptrace, snaptrace + snaptrace_len, false, &realm)) { ... } ceph_update_snap_trace() then decodes a struct ceph_mds_snap_realm from snaptrace using ceph_decode_need(&p, e, sizeof(*ri), bad) with the attacker-supplied fake end e == snaptrace + snaptrace_len. With snaptrace_len == 0xFFFFFFFF the bound check is trivially satisfied, ri = p reads sizeof(struct ceph_mds_snap_realm) past the legitimate msg->front buffer, and ri->num_snaps / ri->num_prior_parent_snaps then drive further out-of-bounds reads of the encoded snap arrays. The eleven msg_version >= 2 .. msg_version >= 12 decoder blocks above the op switch each catch this OOB through their ceph_decode_*_safe() / ceph_decode_need() helpers, but they sit behind a hdr.version-gated if, so a malicious or compromised MDS that sets msg->hdr.version = 1 reaches the IMPORT path with no version-gated decoder having validated snap_trace_len. The shape has been present since ceph_handle_caps() was introduced. Validate snap_trace_len against the message front buffer before consuming it, using the canonical ceph_decode_need() / ceph_has_room() helper. The helper bounds the length with subtraction (n <= end - p, guarded by end >= p) rather than pointer addition, so it is wrap-safe for the attacker-controlled u32 length on 32-bit builds where p + snap_trace_len could overflow the address space. This matches the rest of the ceph decode path (e.g. the pool_ns_len check a few lines below), and the existing goto bad cleanup already covers this exit path. Cc: stable@vger.kernel.org Fixes: a8599bd821d0 ("ceph: capability management") Signed-off-by: Bryam Vargas Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

ceph: put folios not suitable for writeback

2026-05-11T08:39:22+00:00

The batch holds references to the folios (see `filemap_get_folios`, `folio_batch_release`), so we need to `folio_put` the folios we remove. Tested on v6.18. Cc: stable@vger.kernel.org Link: https://tracker.ceph.com/issues/74156 Signed-off-by: Hristo Venev Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov

ceph: add ceph_has_realms_with_quotas() check to ceph_quota_update_statfs()

2026-05-11T08:39:22+00:00

When MDS rejects a session, remove_session_caps() -> __ceph_remove_cap() -> ceph_change_snap_realm() clears i_snap_realm for every inode that loses its last cap. The realm is restored once caps are re-granted after reconnect. It is not a real error and this patch changes pr_err_ratelimited_client() on doutc(). Every quota methods ceph_quota_is_max_files_exceeded(), ceph_quota_is_max_bytes_exceeded(), ceph_quota_is_max_bytes_approaching() calls ceph_has_realms_with_quotas() check. This patch adds the missing ceph_has_realms_with_quotas() call into ceph_quota_update_statfs(). [ idryomov: add braces around both arms of multiline ifs ] Signed-off-by: Viacheslav Dubeyko Reviewed-by: Alex Markuze Signed-off-by: Ilya Dryomov

ceph: fix BUG_ON in __ceph_build_xattrs_blob() due to stale blob size

2026-05-11T08:39:22+00:00

The generic/642 test-case can reproduce the kernel crash: [40243.605254] ------------[ cut here ]------------ [40243.605956] kernel BUG at fs/ceph/xattr.c:918! [40243.607142] Oops: invalid opcode: 0000 [#1] SMP PTI [40243.608067] CPU: 7 UID: 0 PID: 498762 Comm: kworker/7:1 Not tainted 7.0.0-rc7+ #3 PREEMPT(full) [40243.609700] Hardware name: QEMU Ubuntu 25.10 PC v2 (i440FX + PIIX, + 10.1 machine, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [40243.611820] Workqueue: ceph-msgr ceph_con_workfn [40243.612715] RIP: 0010:__ceph_build_xattrs_blob+0x1b8/0x1e0 [40243.613731] Code: 0f 84 82 fe ff ff e9 cf 8e 56 ff 48 8d 65 e8 31 c0 5b 41 5c 41 5d 5d 31 d2 31 c9 31 f6 31 ff 45 31 c0 45 31 c9 c3 cc cc cc cc <0f> 0b 4c 8b 62 08 41 8b 85 24 07 00 00 49 83 c4 04 41 89 44 24 fc [40243.616888] RSP: 0018:ffffcc80c4d4b688 EFLAGS: 00010287 [40243.617773] RAX: 0000000000010026 RBX: 0000000000000001 RCX: 0000000000000000 [40243.618928] RDX: ffff8a773798dee0 RSI: 0000000000000000 RDI: 0000000000000000 [40243.620158] RBP: ffffcc80c4d4b6a0 R08: 0000000000000000 R09: 0000000000000000 [40243.621573] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8a75f3b58000 [40243.622907] R13: ffff8a75f3b58000 R14: 0000000000000080 R15: 000000000000bffd [40243.624054] FS: 0000000000000000(0000) GS:ffff8a787d1b4000(0000) knlGS:0000000000000000 [40243.625331] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [40243.626269] CR2: 000072f390b623c0 CR3: 000000011c02a003 CR4: 0000000000372ef0 [40243.627408] Call Trace: [40243.627839] [40243.628188] __prep_cap+0x3fd/0x4a0 [40243.628789] ? do_raw_spin_unlock+0x4e/0xe0 [40243.629474] ceph_check_caps+0x46a/0xc80 [40243.630094] ? __lock_acquire+0x4a2/0x2650 [40243.630773] ? find_held_lock+0x31/0x90 [40243.631347] ? handle_cap_grant+0x79f/0x1060 [40243.632068] ? lock_release+0xd9/0x300 [40243.632696] ? __mutex_unlock_slowpath+0x3e/0x340 [40243.633429] ? lock_release+0xd9/0x300 [40243.634052] handle_cap_grant+0xcf6/0x1060 [40243.634745] ceph_handle_caps+0x122b/0x2110 [40243.635415] mds_dispatch+0x5bd/0x2160 [40243.636034] ? ceph_con_process_message+0x65/0x190 [40243.636828] ? lock_release+0xd9/0x300 [40243.637431] ceph_con_process_message+0x7a/0x190 [40243.638184] ? kfree+0x311/0x4f0 [40243.638749] ? kfree+0x311/0x4f0 [40243.639268] process_message+0x16/0x1a0 [40243.639915] ? sg_free_table+0x39/0x90 [40243.640572] ceph_con_v2_try_read+0xf58/0x2120 [40243.641255] ? lock_acquire+0xc8/0x300 [40243.641863] ceph_con_workfn+0x151/0x820 [40243.642493] process_one_work+0x22f/0x630 [40243.643093] ? process_one_work+0x254/0x630 [40243.643770] worker_thread+0x1e2/0x400 [40243.644332] ? __pfx_worker_thread+0x10/0x10 [40243.645020] kthread+0x109/0x140 [40243.645560] ? __pfx_kthread+0x10/0x10 [40243.646125] ret_from_fork+0x3f8/0x480 [40243.646752] ? __pfx_kthread+0x10/0x10 [40243.647316] ? __pfx_kthread+0x10/0x10 [40243.647919] ret_from_fork_asm+0x1a/0x30 [40243.648556] [40243.648902] Modules linked in: overlay hctr2 libpolyval chacha libchacha adiantum libnh libpoly1305 essiv intel_rapl_msr intel_rapl_common intel_uncore_frequency_common skx_edac_common nfit kvm_intel kvm irqbypass joydev ghash_clmulni_intel aesni_intel rapl input_leds mac_hid psmouse vga16fb serio_raw vgastate floppy i2c_piix4 pata_acpi bochs qemu_fw_cfg i2c_smbus sch_fq_codel rbd dm_crypt msr parport_pc ppdev lp parport efi_pstore [40243.654766] ---[ end trace 0000000000000000 ]--- Commit d93231a6bc8a ("ceph: prevent a client from exceeding the MDS maximum xattr size") moved the required_blob_size computation to before the __build_xattrs() call, introducing a race. __build_xattrs() releases and reacquires i_ceph_lock during execution. In that window, handle_cap_grant() may update i_xattrs.blob with a newer MDS-provided blob and bump i_xattrs.version. When __build_xattrs() detects that index_version < version, it destroys and rebuilds the entire xattr rb-tree from the new blob, potentially increasing count, names_size, and vals_size. The prealloc_blob size check that follows still uses the stale required_blob_size computed before the rebuild, so it passes even when prealloc_blob is too small for the now-larger tree. After __set_xattr() adds one more xattr on top, __ceph_build_xattrs_blob() is called from the cap flush path and hits: BUG_ON(need > ci->i_xattrs.prealloc_blob->alloc_len); Fix this by recomputing required_blob_size after __build_xattrs() returns, using the current tree state. Also re-validate against m_max_xattr_size to fall back to the sync path if the rebuilt tree now exceeds the MDS limit. Cc: stable@vger.kernel.org Fixes: d93231a6bc8a ("ceph: prevent a client from exceeding the MDS maximum xattr size") Signed-off-by: Viacheslav Dubeyko Reviewed-by: Alex Markuze Signed-off-by: Ilya Dryomov

ceph: fix a buffer leak in __ceph_setxattr()

2026-05-11T08:39:22+00:00

The old_blob in __ceph_setxattr() can store ci->i_xattrs.prealloc_blob value during the retry. However, it is never called the ceph_buffer_put() for the old_blob object. This patch fixes the issue of the buffer leak. Cc: stable@vger.kernel.org Signed-off-by: Viacheslav Dubeyko Reviewed-by: Alex Markuze Signed-off-by: Ilya Dryomov