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Tengda Wu d6bec89235 x86/dumpstack: Prevent KASAN false positive warnings in __show_regs() 
[ Upstream commit ced37e9cea ]

When triggering a stack dump via sysrq (echo t > /proc/sysrq-trigger),
KASAN may report false-positive out-of-bounds access:

  BUG: KASAN: out-of-bounds in __show_regs+0x4b/0x340
  Call Trace:
    dump_stack_lvl
    print_address_description.constprop.0
    print_report
    __show_regs
    show_trace_log_lvl
    sched_show_task
    show_state_filter
    sysrq_handle_showstate
    __handle_sysrq
    write_sysrq_trigger
    proc_reg_write
    vfs_write
    ksys_write
    do_syscall_64
    entry_SYSCALL_64_after_hwframe

The issue occurs as follows:

  Task A (walk other tasks' stacks)           Task B (running)
  1. echo t > /proc/sysrq-trigger
  show_trace_log_lvl
    regs = unwind_get_entry_regs()
    show_regs_if_on_stack(regs)
                                              2. The stack value pointed by
                                                 `regs` keeps changing, and
                                                 so are the tags in its
                                                 KASAN shadow region.
      __show_regs(regs)
        regs->ax, regs->bx, ...
          3. hit KASAN redzones, OOB

When task A walks task B's stack without suspending it, the continuous changes
in task B's stack (and corresponding KASAN shadow tags) may cause task A to
hit KASAN redzones when accessing obsolete values on the stack, resulting in
false positive reports.

Simply stopping the task before unwinding is not a viable fix, as it would
alter the state intended to inspect. This is especially true for diagnosing
misbehaving tasks (e.g., in a hard lockup), where stopping might fail or hide
the root cause by changing the call stack.

Therefore, fix this by disabling KASAN checks during asynchronous stack
unwinding, which is identified when the unwinding task does not match the
current task (task != current).

  [ bp: Align arguments on function's opening brace. ]

Fixes: 3b3fa11bc7 ("x86/dumpstack: Print any pt_regs found on the stack")
Signed-off-by: Tengda Wu <wutengda@huaweicloud.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://patch.msgid.link/all/20251023090632.269121-1-wutengda@huaweicloud.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-12-18 13:54:50 +01:00
arch x86/dumpstack: Prevent KASAN false positive warnings in __show_regs() 2025-12-18 13:54:50 +01:00
block block/mq-deadline: Switch back to a single dispatch list 2025-12-18 13:54:45 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate_id 2025-12-18 13:54:47 +01:00
Documentation dt-bindings: clock: qcom,x1e80100-gcc: Add missing USB4 clocks/resets 2025-12-18 13:54:44 +01:00
drivers mtd: rawnand: lpc32xx_slc: fix GPIO descriptor leak on probe error and remove 2025-12-18 13:54:49 +01:00
fs ntfs3: Fix uninit buffer allocated by __getname() 2025-12-18 13:54:43 +01:00
include perf: Remove get_perf_callchain() init_nr argument 2025-12-18 13:54:49 +01:00
init init: handle bootloader identifier in kernel parameters 2025-10-19 16:33:50 +02:00
io_uring io_uring/napi: fix io_napi_entry RCU accesses 2025-11-24 10:36:06 +01:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:11:22 +01:00
kernel task_work: Fix NMI race condition 2025-12-18 13:54:50 +01:00
lib maple_tree: fix tracepoint string pointers 2025-12-01 11:43:39 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm/huge_memory: fix NULL pointer deference when splitting folio 2025-12-07 06:25:02 +09:00
net sctp: Defer SCTP_DBG_OBJCNT_DEC() to sctp_destroy_sock(). 2025-12-18 13:54:48 +01:00
rust rust: kbuild: workaround rustdoc doctests modifier bug 2025-11-24 10:36:07 +01:00
samples samples: work around glibc redefining some of our defines wrong 2025-12-12 18:37:21 +01:00
scripts kconfig/nconf: Initialize the default locale at startup 2025-12-01 11:43:36 +01:00
security smack: fix bug: setting task label silently ignores input garbage 2025-12-18 13:54:40 +01:00
sound ALSA: usb-audio: Add native DSD quirks for PureAudio DAC series 2025-12-12 18:37:20 +01:00
tools perf annotate: Check return value of evsel__get_arch() properly 2025-12-18 13:54:45 +01:00
usr kbuild: uapi: Strip comments before size type check 2025-11-13 15:34:35 -05:00
virt KVM: guest_memfd: Remove bindings on memslot deletion when gmem is dying 2025-11-24 10:36:06 +01:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-08-01 09:48:44 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: introduce .clippy.toml 2025-03-13 13:01:42 +01:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS staging: rtl8712: Remove driver using deprecated API wext 2025-12-07 06:25:02 +09:00
Makefile Linux 6.12.62 2025-12-12 18:37:22 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.