From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions When using eBPF to probe CS CALL instructions within a function, a crash can be triggered. The eBPF tool probes offset 257 of the __hrtimer_run_queues() function: <__hrtimer_run_queues+249>: nopl 0x0(%rax,%rax,1) <__hrtimer_run_queues+254>: mov %r14,%rdi <__hrtimer_run_queues+257>: cs call <__x86_indirect_thunk_r12> <__hrtimer_run_queues+263>: mov %eax,%r12d <__hrtimer_run_queues+266>: xchg %ax,%ax <__hrtimer_run_queues+268>: mov %r13,%rdi Which triggers this crash: BUG: unable to handle page fault for address: 00000000000f41c9 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP NOPTI CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P RIP: 0010:__hrtimer_run_queues+0x106/0x230 Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is at the 6th byte of the above CS CALL instruction. Since the CS CALL instruction occupies 6 bytes, the exception occurred in the middle of that call instruction. The root cause is that when using eBPF tools to probe in the middle of a function, a kprobe with INT3 is used as the underlying implementation. During single-step emulation of the original CALL instruction, int3_emulate_call() assumes that the probed CALL instruction is 5 bytes long. However, the actual CS-prefixed CALL instruction occupies 6 bytes, so it constructs an incorrect exception return address. When the CPU returns from the kprobe handler, the next instruction to be executed is at the address of the last byte of that CS CALL instruction. Coincidentally, starting from that address, the CPU fetches and decodes a completely different instruction, which ultimately triggers a kernel crash. Fix the issue by using the actual instruction length obtained from the instruction decoder when constructing the exception return address, rather than relying on the hardcoded CALL_INSN_SIZE macro. [ mingo: Refined the changelog ] Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step") Suggested-by: Masami Hiramatsu (Google) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- fs/ceph/strings.c | 130 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 130 insertions(+) create mode 100644 fs/ceph/strings.c (limited to 'fs/ceph/strings.c') diff --git a/fs/ceph/strings.c b/fs/ceph/strings.c new file mode 100644 index 000000000..e36e8948e --- /dev/null +++ b/fs/ceph/strings.c @@ -0,0 +1,130 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Ceph fs string constants + */ +#include +#include + + +const char *ceph_mds_state_name(int s) +{ + switch (s) { + /* down and out */ + case CEPH_MDS_STATE_DNE: return "down:dne"; + case CEPH_MDS_STATE_STOPPED: return "down:stopped"; + /* up and out */ + case CEPH_MDS_STATE_BOOT: return "up:boot"; + case CEPH_MDS_STATE_STANDBY: return "up:standby"; + case CEPH_MDS_STATE_STANDBY_REPLAY: return "up:standby-replay"; + case CEPH_MDS_STATE_REPLAYONCE: return "up:oneshot-replay"; + case CEPH_MDS_STATE_CREATING: return "up:creating"; + case CEPH_MDS_STATE_STARTING: return "up:starting"; + /* up and in */ + case CEPH_MDS_STATE_REPLAY: return "up:replay"; + case CEPH_MDS_STATE_RESOLVE: return "up:resolve"; + case CEPH_MDS_STATE_RECONNECT: return "up:reconnect"; + case CEPH_MDS_STATE_REJOIN: return "up:rejoin"; + case CEPH_MDS_STATE_CLIENTREPLAY: return "up:clientreplay"; + case CEPH_MDS_STATE_ACTIVE: return "up:active"; + case CEPH_MDS_STATE_STOPPING: return "up:stopping"; + } + return "???"; +} + +const char *ceph_session_op_name(int op) +{ + switch (op) { + case CEPH_SESSION_REQUEST_OPEN: return "request_open"; + case CEPH_SESSION_OPEN: return "open"; + case CEPH_SESSION_REQUEST_CLOSE: return "request_close"; + case CEPH_SESSION_CLOSE: return "close"; + case CEPH_SESSION_REQUEST_RENEWCAPS: return "request_renewcaps"; + case CEPH_SESSION_RENEWCAPS: return "renewcaps"; + case CEPH_SESSION_STALE: return "stale"; + case CEPH_SESSION_RECALL_STATE: return "recall_state"; + case CEPH_SESSION_FLUSHMSG: return "flushmsg"; + case CEPH_SESSION_FLUSHMSG_ACK: return "flushmsg_ack"; + case CEPH_SESSION_FORCE_RO: return "force_ro"; + case CEPH_SESSION_REJECT: return "reject"; + case CEPH_SESSION_REQUEST_FLUSH_MDLOG: return "flush_mdlog"; + } + return "???"; +} + +const char *ceph_mds_op_name(int op) +{ + switch (op) { + case CEPH_MDS_OP_LOOKUP: return "lookup"; + case CEPH_MDS_OP_LOOKUPHASH: return "lookuphash"; + case CEPH_MDS_OP_LOOKUPPARENT: return "lookupparent"; + case CEPH_MDS_OP_LOOKUPINO: return "lookupino"; + case CEPH_MDS_OP_LOOKUPNAME: return "lookupname"; + case CEPH_MDS_OP_GETATTR: return "getattr"; + case CEPH_MDS_OP_GETVXATTR: return "getvxattr"; + case CEPH_MDS_OP_SETXATTR: return "setxattr"; + case CEPH_MDS_OP_SETATTR: return "setattr"; + case CEPH_MDS_OP_RMXATTR: return "rmxattr"; + case CEPH_MDS_OP_SETLAYOUT: return "setlayou"; + case CEPH_MDS_OP_SETDIRLAYOUT: return "setdirlayout"; + case CEPH_MDS_OP_READDIR: return "readdir"; + case CEPH_MDS_OP_MKNOD: return "mknod"; + case CEPH_MDS_OP_LINK: return "link"; + case CEPH_MDS_OP_UNLINK: return "unlink"; + case CEPH_MDS_OP_RENAME: return "rename"; + case CEPH_MDS_OP_MKDIR: return "mkdir"; + case CEPH_MDS_OP_RMDIR: return "rmdir"; + case CEPH_MDS_OP_SYMLINK: return "symlink"; + case CEPH_MDS_OP_CREATE: return "create"; + case CEPH_MDS_OP_OPEN: return "open"; + case CEPH_MDS_OP_LOOKUPSNAP: return "lookupsnap"; + case CEPH_MDS_OP_LSSNAP: return "lssnap"; + case CEPH_MDS_OP_MKSNAP: return "mksnap"; + case CEPH_MDS_OP_RMSNAP: return "rmsnap"; + case CEPH_MDS_OP_RENAMESNAP: return "renamesnap"; + case CEPH_MDS_OP_SETFILELOCK: return "setfilelock"; + case CEPH_MDS_OP_GETFILELOCK: return "getfilelock"; + } + return "???"; +} + +const char *ceph_cap_op_name(int op) +{ + switch (op) { + case CEPH_CAP_OP_GRANT: return "grant"; + case CEPH_CAP_OP_REVOKE: return "revoke"; + case CEPH_CAP_OP_TRUNC: return "trunc"; + case CEPH_CAP_OP_EXPORT: return "export"; + case CEPH_CAP_OP_IMPORT: return "import"; + case CEPH_CAP_OP_UPDATE: return "update"; + case CEPH_CAP_OP_DROP: return "drop"; + case CEPH_CAP_OP_FLUSH: return "flush"; + case CEPH_CAP_OP_FLUSH_ACK: return "flush_ack"; + case CEPH_CAP_OP_FLUSHSNAP: return "flushsnap"; + case CEPH_CAP_OP_FLUSHSNAP_ACK: return "flushsnap_ack"; + case CEPH_CAP_OP_RELEASE: return "release"; + case CEPH_CAP_OP_RENEW: return "renew"; + } + return "???"; +} + +const char *ceph_lease_op_name(int o) +{ + switch (o) { + case CEPH_MDS_LEASE_REVOKE: return "revoke"; + case CEPH_MDS_LEASE_RELEASE: return "release"; + case CEPH_MDS_LEASE_RENEW: return "renew"; + case CEPH_MDS_LEASE_REVOKE_ACK: return "revoke_ack"; + } + return "???"; +} + +const char *ceph_snap_op_name(int o) +{ + switch (o) { + case CEPH_SNAP_OP_UPDATE: return "update"; + case CEPH_SNAP_OP_CREATE: return "create"; + case CEPH_SNAP_OP_DESTROY: return "destroy"; + case CEPH_SNAP_OP_SPLIT: return "split"; + } + return "???"; +} -- cgit v1.3.1