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Filename Latest commit message Latest commit date
yangerkun 384e15fc42 locks: fix a potential use-after-free problem when wakeup a waiter
[ Upstream commit 6d390e4b5d48ec03bb87e63cf0a2bff5f4e116da ]

'16306a61d3 ("fs/locks: always delete_block after waiting.")' add the
logic to check waiter->fl_blocker without blocked_lock_lock. And it will
trigger a UAF when we try to wakeup some waiter:

Thread 1 has create a write flock a on file, and now thread 2 try to
unlock and delete flock a, thread 3 try to add flock b on the same file.

Thread2                         Thread3
                                flock syscall(create flock b)
	                        ...flock_lock_inode_wait
				    flock_lock_inode(will insert
				    our fl_blocked_member list
				    to flock a's fl_blocked_requests)
				   sleep
flock syscall(unlock)
...flock_lock_inode_wait
    locks_delete_lock_ctx
    ...__locks_wake_up_blocks
        __locks_delete_blocks(
	b->fl_blocker = NULL)
	...
                                   break by a signal
				   locks_delete_block
				    b->fl_blocker == NULL &&
				    list_empty(&b->fl_blocked_requests)
	                            success, return directly
				 locks_free_lock b
	wake_up(&b->fl_waiter)
	trigger UAF

Fix it by remove this logic, and this patch may also fix CVE-2019-19769.

Cc: stable@vger.kernel.org
Fixes: 16306a61d3 ("fs/locks: always delete_block after waiting.")
Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-03-25 08:25:41 +01:00
arch ARM: 8961/2: Fix Kbuild issue caused by per-task stack protector GCC plugin 2020-03-21 08:11:59 +01:00
block blk-mq: insert flush request to the front of dispatch queue 2020-03-21 08:11:57 +01:00
certs
crypto crypto: rename sm3-256 to sm3 in hash_algo_name 2020-02-28 17:22:26 +01:00
Documentation ACPI: watchdog: Allow disabling WDAT at boot 2020-03-21 08:11:47 +01:00
drivers HID: add ALWAYS_POLL quirk to lenovo pixart mouse 2020-03-21 08:11:59 +01:00
fs locks: fix a potential use-after-free problem when wakeup a waiter 2020-03-25 08:25:41 +01:00
include driver code: clarify and fix platform device DMA mask allocation 2020-03-18 07:17:56 +01:00
init kbuild: remove header compile test 2020-03-05 16:43:47 +01:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-28 17:22:20 +01:00
kernel signal: avoid double atomic counter increments for user accounting 2020-03-21 08:11:53 +01:00
lib kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
LICENSES
mm mm: slub: add missing TID bump in kmem_cache_alloc_bulk() 2020-03-21 08:11:58 +01:00
net ipv4: ensure rcu_read_lock() in cipso_v4_error() 2020-03-21 08:11:59 +01:00
samples
scripts kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
security efi: Only print errors about failing to get certs if EFI vars are found 2020-03-12 13:00:14 +01:00
sound ALSA: hda/realtek - Fixed one of HP ALC671 platform Headset Mic supported 2020-03-18 07:17:38 +01:00
tools selftests/rseq: Fix out-of-tree compilation 2020-03-21 08:11:49 +01:00
usr kbuild: fix 'No such file or directory' warning when cleaning 2020-03-12 13:00:09 +01:00
virt KVM: Check for a bad hva before dropping into the ghc slow path 2020-03-05 16:43:48 +01:00
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Makefile Linux 5.4.27 2020-03-21 08:12:00 +01:00
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
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    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.