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Marco Elver 45eec49fa2 kcsan, seqlock: Fix incorrect assumption in read_seqbegin() 
[ Upstream commit 183ec5f26b ]

During testing of the preceding changes, I noticed that in some cases,
current->kcsan_ctx.in_flat_atomic remained true until task exit. This is
obviously wrong, because _all_ accesses for the given task will be
treated as atomic, resulting in false negatives i.e. missed data races.

Debugging led to fs/dcache.c, where we can see this usage of seqlock:

	struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name)
	{
		struct dentry *dentry;
		unsigned seq;

		do {
			seq = read_seqbegin(&rename_lock);
			dentry = __d_lookup(parent, name);
			if (dentry)
				break;
		} while (read_seqretry(&rename_lock, seq));
	[...]

As can be seen, read_seqretry() is never called if dentry != NULL;
consequently, current->kcsan_ctx.in_flat_atomic will never be reset to
false by read_seqretry().

Give up on the wrong assumption of "assume closing read_seqretry()", and
rely on the already-present annotations in read_seqcount_begin/retry().

Fixes: 88ecd153be ("seqlock, kcsan: Add annotations for KCSAN")
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241104161910.780003-6-elver@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-12-09 10:31:51 +01:00
arch x86/unwind/orc: Fix unwind for newly forked tasks 2024-12-09 10:31:50 +01:00
block block: fix bio_split_rw_at to take zone_write_granularity into account 2024-12-09 10:31:45 +01:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: pcrypt - Call crypto layer directly when padata_do_parallel() return -EBUSY 2024-12-09 10:31:48 +01:00
Documentation kcsan, seqlock: Support seqcount_latch_t 2024-12-09 10:31:51 +01:00
drivers crypto: cavium - Fix an error handling path in cpt_ucode_load_fw() 2024-12-09 10:31:50 +01:00
fs ext4: fix race in buffer_head read fault injection 2024-12-09 10:31:46 +01:00
include kcsan, seqlock: Fix incorrect assumption in read_seqbegin() 2024-12-09 10:31:51 +01:00
init initramfs: avoid filename buffer overrun 2024-12-09 10:31:44 +01:00
io_uring io_uring: fix possible deadlock in io_register_iowq_max_workers() 2024-11-17 15:08:58 +01:00
ipc sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table) 2024-08-11 12:47:13 +02:00
kernel time: Fix references to _msecs_to_jiffies() handling of values 2024-12-09 10:31:50 +01:00
lib lib/buildid: Fix build ID parsing logic 2024-11-22 15:38:36 +01:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/damon/core: copy nr_accesses when splitting region 2024-11-22 15:38:37 +01:00
net mptcp: fix possible integer overflow in mptcp_reset_tout_timer 2024-12-09 10:31:42 +01:00
rust rust: sync: require T: Sync for LockedBy::access 2024-10-10 11:57:44 +02:00
samples samples: pktgen: correct dev to DEV 2024-11-22 15:38:32 +01:00
scripts kconfig: qconf: fix buffer overflow in debug links 2024-10-10 11:58:01 +02:00
security ima: fix buffer overrun in ima_eventdigest_init_common 2024-11-22 15:38:34 +01:00
sound ALSA: usb-audio: Fix Yamaha P-125 Quirk Entry 2024-12-09 10:31:40 +01:00
tools thermal/lib: Fix memory leak on error in thermal_genl_auto() 2024-12-09 10:31:50 +01:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Use dedicated mutex to protect kvm_usage_count to avoid deadlock 2024-10-04 16:29:47 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-04 16:29:44 +02:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.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 USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
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 membarrier: riscv: Add full memory barrier in switch_mm() 2024-09-12 11:11:45 +02:00
Makefile Linux 6.6.63 2024-11-22 15:38:37 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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 Restructured Text 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.