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 --- rust/zerocopy-derive/lib.rs | 180 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 180 insertions(+) create mode 100644 rust/zerocopy-derive/lib.rs (limited to 'rust/zerocopy-derive/lib.rs') diff --git a/rust/zerocopy-derive/lib.rs b/rust/zerocopy-derive/lib.rs new file mode 100644 index 000000000..d387de368 --- /dev/null +++ b/rust/zerocopy-derive/lib.rs @@ -0,0 +1,180 @@ +// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT +// +// Copyright 2019 The Fuchsia Authors +// +// Licensed under a BSD-style license , Apache License, Version 2.0 +// , or the MIT +// license , at your option. +// This file may not be copied, modified, or distributed except according to +// those terms. + +//! Derive macros for [zerocopy]'s traits. +//! +//! [zerocopy]: https://docs.rs/zerocopy + +// Sometimes we want to use lints which were added after our MSRV. +// `unknown_lints` is `warn` by default and we deny warnings in CI, so without +// this attribute, any unknown lint would cause a CI failure when testing with +// our MSRV. +#![allow(unknown_lints)] +#![deny(renamed_and_removed_lints)] +#![deny( + clippy::all, + clippy::missing_safety_doc, + clippy::multiple_unsafe_ops_per_block, + clippy::undocumented_unsafe_blocks +)] +// We defer to own discretion on type complexity. +#![allow(clippy::type_complexity)] +// Inlining format args isn't supported on our MSRV. +#![allow(clippy::uninlined_format_args)] +#![deny( + rustdoc::bare_urls, + rustdoc::broken_intra_doc_links, + rustdoc::invalid_codeblock_attributes, + rustdoc::invalid_html_tags, + rustdoc::invalid_rust_codeblocks, + rustdoc::missing_crate_level_docs, + rustdoc::private_intra_doc_links +)] +#![recursion_limit = "128"] + +macro_rules! ident { + (($fmt:literal $(, $arg:expr)*), $span:expr) => { + syn::Ident::new(&format!($fmt $(, crate::util::to_ident_str($arg))*), $span) + }; +} + +mod derive; +#[cfg(test)] +mod output_tests; +mod repr; +mod util; + +use syn::{DeriveInput, Error}; + +use crate::util::*; + +// FIXME(https://github.com/rust-lang/rust/issues/54140): Some errors could be +// made better if we could add multiple lines of error output like this: +// +// error: unsupported representation +// --> enum.rs:28:8 +// | +// 28 | #[repr(transparent)] +// | +// help: required by the derive of FromBytes +// +// Instead, we have more verbose error messages like "unsupported representation +// for deriving FromZeros, FromBytes, IntoBytes, or Unaligned on an enum" +// +// This will probably require Span::error +// (https://doc.rust-lang.org/nightly/proc_macro/struct.Span.html#method.error), +// which is currently unstable. Revisit this once it's stable. + +/// Defines a derive function named `$outer` which parses its input +/// `TokenStream` as a `DeriveInput` and then invokes the `$inner` function. +/// +/// Note that the separate `$outer` parameter is required - proc macro functions +/// are currently required to live at the crate root, and so the caller must +/// specify the name in order to avoid name collisions. +macro_rules! derive { + ($trait:ident => $outer:ident => $inner:path) => { + #[proc_macro_derive($trait, attributes(zerocopy))] + pub fn $outer(ts: proc_macro::TokenStream) -> proc_macro::TokenStream { + let ast = syn::parse_macro_input!(ts as DeriveInput); + let ctx = match Ctx::try_from_derive_input(ast) { + Ok(ctx) => ctx, + Err(e) => return e.into_compile_error().into(), + }; + let ts = $inner(&ctx, Trait::$trait).into_ts(); + // We wrap in `const_block` as a backstop in case any derive fails + // to wrap its output in `const_block` (and thus fails to annotate) + // with the full set of `#[allow(...)]` attributes). + let ts = const_block([Some(ts)]); + #[cfg(test)] + crate::util::testutil::check_hygiene(ts.clone()); + ts.into() + } + }; +} + +trait IntoTokenStream { + fn into_ts(self) -> proc_macro2::TokenStream; +} + +impl IntoTokenStream for proc_macro2::TokenStream { + fn into_ts(self) -> proc_macro2::TokenStream { + self + } +} + +impl IntoTokenStream for Result { + fn into_ts(self) -> proc_macro2::TokenStream { + match self { + Ok(ts) => ts, + Err(err) => err.to_compile_error(), + } + } +} + +derive!(KnownLayout => derive_known_layout => crate::derive::known_layout::derive); +derive!(Immutable => derive_immutable => crate::derive::derive_immutable); +derive!(TryFromBytes => derive_try_from_bytes => crate::derive::try_from_bytes::derive_try_from_bytes); +derive!(FromZeros => derive_from_zeros => crate::derive::from_bytes::derive_from_zeros); +derive!(FromBytes => derive_from_bytes => crate::derive::from_bytes::derive_from_bytes); +derive!(IntoBytes => derive_into_bytes => crate::derive::into_bytes::derive_into_bytes); +derive!(Unaligned => derive_unaligned => crate::derive::unaligned::derive_unaligned); +derive!(ByteHash => derive_hash => crate::derive::derive_hash); +derive!(ByteEq => derive_eq => crate::derive::derive_eq); +derive!(SplitAt => derive_split_at => crate::derive::derive_split_at); + +#[cfg_attr(not(zerocopy_unstable_linux), doc(hidden))] +#[proc_macro_derive(most_traits, attributes(zerocopy))] +pub fn most_traits(ts: proc_macro::TokenStream) -> proc_macro::TokenStream { + let ast = syn::parse_macro_input!(ts as DeriveInput); + let ctx = match Ctx::try_from_derive_input(ast) { + Ok(ctx) => ctx, + Err(e) => return e.into_compile_error().into(), + } + .skip_on_error(); + + // top-level traits for which to attempt a derive + let derives: [(fn(&Ctx, Trait) -> _, _); 6] = [ + (crate::derive::known_layout::derive, Trait::KnownLayout), + (crate::derive::derive_immutable, Trait::Immutable), + (crate::derive::from_bytes::derive_from_bytes, Trait::FromBytes), + (crate::derive::into_bytes::derive_into_bytes, Trait::IntoBytes), + (crate::derive::derive_split_at, Trait::SplitAt), + (crate::derive::unaligned::derive_unaligned, Trait::Unaligned), + ]; + + let mut tokens = proc_macro2::TokenStream::new(); + for (derive, t) in derives { + tokens.extend(derive(&ctx, t)) + } + + // We wrap in `const_block` as a backstop in case any derive fails + // to wrap its output in `const_block` (and thus fails to annotate) + // with the full set of `#[allow(...)]` attributes). + let ts = const_block([Some(tokens)]); + #[cfg(test)] + crate::util::testutil::check_hygiene(ts.clone()); + ts.into() +} + +/// Deprecated: prefer [`FromZeros`] instead. +#[deprecated(since = "0.8.0", note = "`FromZeroes` was renamed to `FromZeros`")] +#[doc(hidden)] +#[proc_macro_derive(FromZeroes)] +pub fn derive_from_zeroes(ts: proc_macro::TokenStream) -> proc_macro::TokenStream { + derive_from_zeros(ts) +} + +/// Deprecated: prefer [`IntoBytes`] instead. +#[deprecated(since = "0.8.0", note = "`AsBytes` was renamed to `IntoBytes`")] +#[doc(hidden)] +#[proc_macro_derive(AsBytes)] +pub fn derive_as_bytes(ts: proc_macro::TokenStream) -> proc_macro::TokenStream { + derive_into_bytes(ts) +} -- cgit v1.3.1