kernel/linux.git/fs/ceph, branch v6.1.186

ceph: fix hanging __ceph_get_caps() with stale mds_wanted

2026-08-23T12:18:31+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: rename _to_client() to _to_fs_client()

2026-08-23T12:18:31+00:00

[ Upstream commit 5995d90d2d19f337df6a50bcf4699ef053214dac ] We need to covert the inode to ceph_client in the following commit, and will add one new helper for that, here we rename the old helper to _fs_client(). Link: https://tracker.ceph.com/issues/61590 Signed-off-by: Xiubo Li Reviewed-by: Patrick Donnelly Reviewed-by: Milind Changire Signed-off-by: Ilya Dryomov Stable-dep-of: 50958bb928ba ("ceph: fix hanging __ceph_get_caps() with stale mds_wanted") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ceph: pass the mdsc to several helpers

2026-08-23T12:18:31+00:00

[ Upstream commit 197b7d792d6aead2e30d4b2c054ffabae2ed73dc ] We will use the 'mdsc' to get the global_id in the following commits. Link: https://tracker.ceph.com/issues/61590 Signed-off-by: Xiubo Li Reviewed-by: Patrick Donnelly Reviewed-by: Milind Changire Signed-off-by: Ilya Dryomov Stable-dep-of: 50958bb928ba ("ceph: fix hanging __ceph_get_caps() with stale mds_wanted") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ceph: avoid fs reclaim while using current->journal_info

2026-08-23T12:18:30+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

2026-08-23T12:18:19+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 pre-auth out-of-bounds read on snaptrace in ceph_handle_caps()

2026-08-19T15:16:07+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: only d_add() negative dentries when they are unhashed

2026-06-19T11:37:20+00:00

[ Upstream commit 803447f93d75ab6e40c85e6d12b5630d281d70d6 ] Ceph can call d_add(dentry, NULL) on a negative dentry that is already present in the primary dcache hash. In the current VFS that is not safe. d_add() goes through __d_add() to __d_rehash(), which unconditionally reinserts dentry->d_hash into the hlist_bl bucket. If the dentry is already hashed, reinserting the same node can corrupt the bucket, including creating a self-loop. Once that happens, __d_lookup() can spin forever in the hlist_bl walk, typically looping only on the d_name.hash mismatch check and eventually triggering RCU stall reports like this one: rcu: INFO: rcu_sched self-detected stall on CPU rcu: 87-....: (2100 ticks this GP) idle=3a4c/1/0x4000000000000000 softirq=25003319/25003319 fqs=829 rcu: (t=2101 jiffies g=79058445 q=698988 ncpus=192) CPU: 87 UID: 2952868916 PID: 3933303 Comm: php-cgi8.3 Not tainted 6.18.17-i1-amd #950 NONE Hardware name: Dell Inc. PowerEdge R7615/0G9DHV, BIOS 1.6.6 09/22/2023 RIP: 0010:__d_lookup+0x46/0xb0 Code: c1 e8 07 48 8d 04 c2 48 8b 00 49 89 fc 49 89 f5 48 89 c3 48 83 e3 fe 48 83 f8 01 77 0f eb 2d 0f 1f 44 00 00 48 8b 1b 48 85 db <74> 20 39 6b 18 75 f3 48 8d 7b 78 e8 ba 85 d0 00 4c 39 63 10 74 1f RSP: 0018:ff745a70c8253898 EFLAGS: 00000282 RAX: ff26e470054cb208 RBX: ff26e470054cb208 RCX: 000000006e958966 RDX: ff26e48267340000 RSI: ff745a70c82539b0 RDI: ff26e458f74655c0 RBP: 000000006e958966 R08: 0000000000000180 R09: 9cd08d909b919a89 R10: ff26e458f74655c0 R11: 0000000000000000 R12: ff26e458f74655c0 R13: ff745a70c82539b0 R14: d0d0d0d0d0d0d0d0 R15: 2f2f2f2f2f2f2f2f FS: 00007f5770896980(0000) GS:ff26e482c5d88000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5764de50c0 CR3: 000000a72abb5001 CR4: 0000000000771ef0 PKRU: 55555554 Call Trace: lookup_fast+0x9f/0x100 walk_component+0x1f/0x150 link_path_walk+0x20e/0x3d0 path_lookupat+0x68/0x180 filename_lookup+0xdc/0x1e0 vfs_statx+0x6c/0x140 vfs_fstatat+0x67/0xa0 __do_sys_newfstatat+0x24/0x60 do_syscall_64+0x6a/0x230 entry_SYSCALL_64_after_hwframe+0x76/0x7e This is reachable with reused cached negative dentries. A Ceph lookup or atomic_open can be handed a negative dentry that is already hashed, and fs/ceph/dir.c then hits one of two paths that incorrectly assume "negative" also means "unhashed": - ceph_finish_lookup(): MDS reply is -ENOENT with no trace -> d_add(dentry, NULL) - ceph_lookup(): local ENOENT fast path for a complete directory with shared caps -> d_add(dentry, NULL) Both paths can therefore re-add an already-hashed negative dentry. Ceph already uses the correct pattern elsewhere: ceph_fill_trace() only calls d_add(dn, NULL) for a negative null-dentry reply when d_unhashed(dn) is true. Fix both fs/ceph/dir.c sites the same way: only call d_add() for a negative dentry when it is actually unhashed. If the negative dentry is already hashed, leave it in place and reuse it as-is. This preserves the existing behavior for unhashed dentries while avoiding d_hash list corruption for reused hashed negatives. Cc: stable@vger.kernel.org Fixes: 2817b000b02c ("ceph: directory operations") Signed-off-by: Max Kellermann Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov [ kept existing dout() debug call instead of upstream's doutc() form when adding the d_unhashed() guard around d_add() ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ceph: fix a buffer leak in __ceph_setxattr()

2026-06-01T15:39:32+00:00

commit 5d3cc36b4e77a27ce7b686b7c59c7072bcb3fa8e upstream. 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 Signed-off-by: Greg Kroah-Hartman

ceph: fix i_nlink underrun during async unlink

2026-03-25T10:03:08+00:00

commit ce0123cbb4a40a2f1bbb815f292b26e96088639f upstream. During async unlink, we drop the `i_nlink` counter before we receive the completion (that will eventually update the `i_nlink`) because "we assume that the unlink will succeed". That is not a bad idea, but it races against deletions by other clients (or against the completion of our own unlink) and can lead to an underrun which emits a WARNING like this one: WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68 Modules linked in: CPU: 85 UID: 3221252029 PID: 25093 Comm: php-cgi8.1 Not tainted 6.14.11-cm4all1-ampere #655 Hardware name: Supermicro ARS-110M-NR/R12SPD-A, BIOS 1.1b 10/17/2023 pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : drop_nlink+0x50/0x68 lr : ceph_unlink+0x6c4/0x720 sp : ffff80012173bc90 x29: ffff80012173bc90 x28: ffff086d0a45aaf8 x27: ffff0871d0eb5680 x26: ffff087f2a64a718 x25: 0000020000000180 x24: 0000000061c88647 x23: 0000000000000002 x22: ffff07ff9236d800 x21: 0000000000001203 x20: ffff07ff9237b000 x19: ffff088b8296afc0 x18: 00000000f3c93365 x17: 0000000000070000 x16: ffff08faffcbdfe8 x15: ffff08faffcbdfec x14: 0000000000000000 x13: 45445f65645f3037 x12: 34385f6369706f74 x11: 0000a2653104bb20 x10: ffffd85f26d73290 x9 : ffffd85f25664f94 x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000002 x5 : 0000000000000081 x4 : 0000000000000481 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff08727d3f91e8 Call trace: drop_nlink+0x50/0x68 (P) vfs_unlink+0xb0/0x2e8 do_unlinkat+0x204/0x288 __arm64_sys_unlinkat+0x3c/0x80 invoke_syscall.constprop.0+0x54/0xe8 do_el0_svc+0xa4/0xc8 el0_svc+0x18/0x58 el0t_64_sync_handler+0x104/0x130 el0t_64_sync+0x154/0x158 In ceph_unlink(), a call to ceph_mdsc_submit_request() submits the CEPH_MDS_OP_UNLINK to the MDS, but does not wait for completion. Meanwhile, between this call and the following drop_nlink() call, a worker thread may process a CEPH_CAP_OP_IMPORT, CEPH_CAP_OP_GRANT or just a CEPH_MSG_CLIENT_REPLY (the latter of which could be our own completion). These will lead to a set_nlink() call, updating the `i_nlink` counter to the value received from the MDS. If that new `i_nlink` value happens to be zero, it is illegal to decrement it further. But that is exactly what ceph_unlink() will do then. The WARNING can be reproduced this way: 1. Force async unlink; only the async code path is affected. Having no real clue about Ceph internals, I was unable to find out why the MDS wouldn't give me the "Fxr" capabilities, so I patched get_caps_for_async_unlink() to always succeed. (Note that the WARNING dump above was found on an unpatched kernel, without this kludge - this is not a theoretical bug.) 2. Add a sleep call after ceph_mdsc_submit_request() so the unlink completion gets handled by a worker thread before drop_nlink() is called. This guarantees that the `i_nlink` is already zero before drop_nlink() runs. The solution is to skip the counter decrement when it is already zero, but doing so without a lock is still racy (TOCTOU). Since ceph_fill_inode() and handle_cap_grant() both hold the `ceph_inode_info.i_ceph_lock` spinlock while set_nlink() runs, this seems like the proper lock to protect the `i_nlink` updates. I found prior art in NFS and SMB (using `inode.i_lock`) and AFS (using `afs_vnode.cb_lock`). All three have the zero check as well. Cc: stable@vger.kernel.org Fixes: 2ccb45462aea ("ceph: perform asynchronous unlink if we have sufficient caps") Signed-off-by: Max Kellermann Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

ceph: supply snapshot context in ceph_zero_partial_object()

2026-03-04T12:20:53+00:00

[ Upstream commit f16bd3fa74a2084ee7e16a8a2be7e7399b970907 ] The ceph_zero_partial_object function was missing proper snapshot context for its OSD write operations, which could lead to data inconsistencies in snapshots. Reproducer: ../src/vstart.sh --new -x --localhost --bluestore ./bin/ceph auth caps client.fs_a mds 'allow rwps fsname=a' mon 'allow r fsname=a' osd 'allow rw tag cephfs data=a' mount -t ceph fs_a@.a=/ /mnt/mycephfs/ -o conf=./ceph.conf dd if=/dev/urandom of=/mnt/mycephfs/foo bs=64K count=1 mkdir /mnt/mycephfs/.snap/snap1 md5sum /mnt/mycephfs/.snap/snap1/foo fallocate -p -o 0 -l 4096 /mnt/mycephfs/foo echo 3 > /proc/sys/vm/drop/caches md5sum /mnt/mycephfs/.snap/snap1/foo # get different md5sum!! Cc: stable@vger.kernel.org Fixes: ad7a60de882ac ("ceph: punch hole support") Signed-off-by: ethanwu Reviewed-by: Viacheslav Dubeyko Tested-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin