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Jinhui Guo 8f4156b242 ipmi: Fix the race between __scan_channels() and deliver_response()
[ Upstream commit 936750fdba ]

The race window between __scan_channels() and deliver_response() causes
the parameters of some channels to be set to 0.

1.[CPUA] __scan_channels() issues an IPMI request and waits with
         wait_event() until all channels have been scanned.
         wait_event() internally calls might_sleep(), which might
         yield the CPU. (Moreover, an interrupt can preempt
         wait_event() and force the task to yield the CPU.)
2.[CPUB] deliver_response() is invoked when the CPU receives the
         IPMI response. After processing a IPMI response,
         deliver_response() directly assigns intf->wchannels to
         intf->channel_list and sets intf->channels_ready to true.
         However, not all channels are actually ready for use.
3.[CPUA] Since intf->channels_ready is already true, wait_event()
         never enters __wait_event(). __scan_channels() immediately
         clears intf->null_user_handler and exits.
4.[CPUB] Once intf->null_user_handler is set to NULL, deliver_response()
         ignores further IPMI responses, leaving the remaining
	 channels zero-initialized and unusable.

CPUA                             CPUB
-------------------------------  -----------------------------
__scan_channels()
 intf->null_user_handler
       = channel_handler;
 send_channel_info_cmd(intf,
       0);
 wait_event(intf->waitq,
       intf->channels_ready);
  do {
   might_sleep();
                                 deliver_response()
                                  channel_handler()
                                   intf->channel_list =
				         intf->wchannels + set;
                                   intf->channels_ready = true;
                                   send_channel_info_cmd(intf,
                                         intf->curr_channel);
   if (condition)
    break;
   __wait_event(wq_head,
          condition);
  } while(0)
 intf->null_user_handler
       = NULL;
                                 deliver_response()
                                  if (!msg->user)
                                   if (intf->null_user_handler)
                                    rv = -EINVAL;
                                  return rv;
-------------------------------  -----------------------------

Fix the race between __scan_channels() and deliver_response() by
deferring both the assignment intf->channel_list = intf->wchannels
and the flag intf->channels_ready = true until all channels have
been successfully scanned or until the IPMI request has failed.

Signed-off-by: Jinhui Guo <guojinhui.liam@bytedance.com>
Message-ID: <20250930074239.2353-2-guojinhui.liam@bytedance.com>
Signed-off-by: Corey Minyard <corey@minyard.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2026-01-08 10:14:09 +01:00
arch x86/fpu: Fix FPU state core dump truncation on CPUs with no extended xfeatures 2026-01-08 10:14:08 +01:00
block block: Use RCU in blk_mq_[un]quiesce_tagset() instead of set->tag_list_lock 2025-12-18 13:55:21 +01:00
certs
crypto crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate_id 2025-12-18 13:54:47 +01:00
Documentation nfsd: rename nfsd_serv_ prefixed methods and variables with nfsd_net_ 2026-01-08 10:14:09 +01:00
drivers
fs nfsd: fix memory leak in nfsd_create_serv error paths 2026-01-08 10:14:09 +01:00
include nfsd: rename nfsd_serv_ prefixed methods and variables with nfsd_net_ 2026-01-08 10:14:09 +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
lib lib/vsprintf: Check pointer before dereferencing in time_and_date() 2025-12-18 13:54:57 +01:00
LICENSES
mm shmem: fix recovery on rename failures 2026-01-08 10:13:54 +01:00
net net/hsr: fix NULL pointer dereference in prp_get_untagged_frame() 2026-01-08 10:14:08 +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 kbuild: Use objtree for module signing key path 2026-01-08 10:13:56 +01:00
security ima: Handle error code returned by ima_filter_rule_match() 2025-12-18 13:55:04 +01:00
sound ASoC: ak4458: remove the reset operation in probe and remove 2026-01-08 10:14:08 +01:00
tools iommufd/selftest: Make it clearer to gcc that the access is not out of bounds 2026-01-08 10:14:02 +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 6.12.63 2025-12-18 13:55:23 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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.