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Filename Latest commit message Latest commit date
Wei Yang 1d1596d68a fs/proc: fix uaf in proc_readdir_de()
[ Upstream commit 895b4c0c79b092d732544011c3cecaf7322c36a1 ]

Pde is erased from subdir rbtree through rb_erase(), but not set the node
to EMPTY, which may result in uaf access.  We should use RB_CLEAR_NODE()
set the erased node to EMPTY, then pde_subdir_next() will return NULL to
avoid uaf access.

We found an uaf issue while using stress-ng testing, need to run testcase
getdent and tun in the same time.  The steps of the issue is as follows:

1) use getdent to traverse dir /proc/pid/net/dev_snmp6/, and current
   pde is tun3;

2) in the [time windows] unregister netdevice tun3 and tun2, and erase
   them from rbtree.  erase tun3 first, and then erase tun2.  the
   pde(tun2) will be released to slab;

3) continue to getdent process, then pde_subdir_next() will return
   pde(tun2) which is released, it will case uaf access.

CPU 0                                      |    CPU 1
-------------------------------------------------------------------------
traverse dir /proc/pid/net/dev_snmp6/      |   unregister_netdevice(tun->dev)   //tun3 tun2
sys_getdents64()                           |
  iterate_dir()                            |
    proc_readdir()                         |
      proc_readdir_de()                    |     snmp6_unregister_dev()
        pde_get(de);                       |       proc_remove()
        read_unlock(&proc_subdir_lock);    |         remove_proc_subtree()
                                           |           write_lock(&proc_subdir_lock);
        [time window]                      |           rb_erase(&root->subdir_node, &parent->subdir);
                                           |           write_unlock(&proc_subdir_lock);
        read_lock(&proc_subdir_lock);      |
        next = pde_subdir_next(de);        |
        pde_put(de);                       |
        de = next;    //UAF                |

rbtree of dev_snmp6
                        |
                    pde(tun3)
                     /    \
                  NULL  pde(tun2)

Link: https://lkml.kernel.org/r/20251025024233.158363-1-albin_yang@163.com
Signed-off-by: Wei Yang <albinwyang@tencent.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: wangzijie <wangzijie1@honor.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-03 12:45:21 +01:00
arch MIPS: Malta: Fix !EVA SOC-it PCI MMIO 2025-12-03 12:45:20 +01:00
block block: use int to store blk_stack_limits() return value 2025-10-29 13:59:46 +01:00
certs
crypto crypto: essiv - Check ssize for decryption and in-place encryption 2025-10-29 13:59:52 +01:00
Documentation arm64: errata: Apply workarounds for Neoverse-V3AE 2025-10-29 14:00:00 +01:00
drivers pmdomain: imx: Fix reference count leak in imx_gpc_remove 2025-12-03 12:45:21 +01:00
fs fs/proc: fix uaf in proc_readdir_de() 2025-12-03 12:45:21 +01:00
include mm/ksm: fix flag-dropping behavior in ksm_madvise 2025-12-03 12:45:18 +01:00
init bpfilter: match bit size of bpfilter_umh to that of the kernel 2025-07-17 18:24:51 +02:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:02:52 +01:00
kernel gcov: add support for GCC 15 2025-12-03 12:45:19 +01:00
lib lib/genalloc: fix device leak in of_gen_pool_get() 2025-10-29 13:59:53 +01:00
LICENSES
mm mm/page_alloc: fix hash table order logging in alloc_large_system_hash() 2025-12-03 12:45:20 +01:00
net net: netpoll: fix incorrect refcount handling causing incorrect cleanup 2025-12-03 12:45:21 +01:00
samples samples: mei: Fix building on musl libc 2025-08-28 16:21:19 +02:00
scripts kconfig/nconf: Initialize the default locale at startup 2025-12-03 12:45:20 +01:00
security KEYS: trusted_tpm1: Compare HMAC values in constant time 2025-10-29 14:00:01 +01:00
sound ALSA: usb-audio: fix uac2 clock source at terminal parser 2025-12-03 12:45:21 +01:00
tools selftests/Makefile: include $(INSTALL_DEP_TARGETS) in clean target to clean net/lib dependency 2025-12-03 12:45:12 +01:00
usr kbuild: hdrcheck: fix cross build with clang 2025-07-17 18:24:51 +02:00
virt KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status 2024-12-19 18:05:04 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Remove *.orig pattern from .gitignore 2024-11-08 16:20:33 +01:00
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS platform: Add Surface platform directory 2025-06-27 11:02:56 +01:00
Makefile Linux 5.4.301 2025-10-29 14:00:02 +01:00
README

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

There are several guides for kernel developers and users. These guides can
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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.