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Filename Latest commit message Latest commit date
Breno Leitao 8e6a50edad net: netpoll: fix incorrect refcount handling causing incorrect cleanup
[ Upstream commit 49c8d2c1f94cc2f4d1a108530d7ba52614b874c2 ]

commit efa95b01da ("netpoll: fix use after free") incorrectly
ignored the refcount and prematurely set dev->npinfo to NULL during
netpoll cleanup, leading to improper behavior and memory leaks.

Scenario causing lack of proper cleanup:

1) A netpoll is associated with a NIC (e.g., eth0) and netdev->npinfo is
   allocated, and refcnt = 1
   - Keep in mind that npinfo is shared among all netpoll instances. In
     this case, there is just one.

2) Another netpoll is also associated with the same NIC and
   npinfo->refcnt += 1.
   - Now dev->npinfo->refcnt = 2;
   - There is just one npinfo associated to the netdev.

3) When the first netpolls goes to clean up:
   - The first cleanup succeeds and clears np->dev->npinfo, ignoring
     refcnt.
     - It basically calls `RCU_INIT_POINTER(np->dev->npinfo, NULL);`
   - Set dev->npinfo = NULL, without proper cleanup
   - No ->ndo_netpoll_cleanup() is either called

4) Now the second target tries to clean up
   - The second cleanup fails because np->dev->npinfo is already NULL.
     * In this case, ops->ndo_netpoll_cleanup() was never called, and
       the skb pool is not cleaned as well (for the second netpoll
       instance)
  - This leaks npinfo and skbpool skbs, which is clearly reported by
    kmemleak.

Revert commit efa95b01da ("netpoll: fix use after free") and adds
clarifying comments emphasizing that npinfo cleanup should only happen
once the refcount reaches zero, ensuring stable and correct netpoll
behavior.

Cc: <stable@vger.kernel.org> # 3.17.x
Cc: Jay Vosburgh <jv@jvosburgh.net>
Fixes: efa95b01da ("netpoll: fix use after free")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20251107-netconsole_torture-v10-1-749227b55f63@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Adjust context ]
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 net: qede: Initialize qede_ll_ops with designated initializer 2025-12-03 12:45:21 +01:00
fs NFS4: Fix state renewals missing after boot 2025-12-03 12:45:16 +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
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
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.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
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.