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Vladimir Oltean a13e690191 net/sched: sch_api: fix xa_insert() error path in tcf_block_get_ext() 
This command:

$ tc qdisc replace dev eth0 ingress_block 1 egress_block 1 clsact
Error: block dev insert failed: -EBUSY.

fails because user space requests the same block index to be set for
both ingress and egress.

[ side note, I don't think it even failed prior to commit 913b47d342
  ("net/sched: Introduce tc block netdev tracking infra"), because this
  is a command from an old set of notes of mine which used to work, but
  alas, I did not scientifically bisect this ]

The problem is not that it fails, but rather, that the second time
around, it fails differently (and irrecoverably):

$ tc qdisc replace dev eth0 ingress_block 1 egress_block 1 clsact
Error: dsa_core: Flow block cb is busy.

[ another note: the extack is added by me for illustration purposes.
  the context of the problem is that clsact_init() obtains the same
  &q->ingress_block pointer as &q->egress_block, and since we call
  tcf_block_get_ext() on both of them, "dev" will be added to the
  block->ports xarray twice, thus failing the operation: once through
  the ingress block pointer, and once again through the egress block
  pointer. the problem itself is that when xa_insert() fails, we have
  emitted a FLOW_BLOCK_BIND command through ndo_setup_tc(), but the
  offload never sees a corresponding FLOW_BLOCK_UNBIND. ]

Even correcting the bad user input, we still cannot recover:

$ tc qdisc replace dev swp3 ingress_block 1 egress_block 2 clsact
Error: dsa_core: Flow block cb is busy.

Basically the only way to recover is to reboot the system, or unbind and
rebind the net device driver.

To fix the bug, we need to fill the correct error teardown path which
was missed during code movement, and call tcf_block_offload_unbind()
when xa_insert() fails.

[ last note, fundamentally I blame the label naming convention in
  tcf_block_get_ext() for the bug. The labels should be named after what
  they do, not after the error path that jumps to them. This way, it is
  obviously wrong that two labels pointing to the same code mean
  something is wrong, and checking the code correctness at the goto site
  is also easier ]

Fixes: 94e2557d08 ("net: sched: move block device tracking into tcf_block_get/put_ext()")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20241023100541.974362-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-10-29 11:45:23 -07:00
arch LoongArch fixes for v6.12-rc5 2024-10-24 14:17:34 -07:00
block block-6.12-20241018 2024-10-18 15:53:00 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes the following issues: 2024-10-16 08:42:54 -07:00
Documentation docs: networking: packet_mmap: replace dead links with archive.org links 2024-10-28 15:47:10 -07:00
drivers netdevsim: Add trailing zero to terminate the string in nsim_nexthop_bucket_activity_write() 2024-10-29 11:43:01 -07:00
fs for-6.12-rc4-tag 2024-10-24 13:04:15 -07:00
include ipv4: ip_tunnel: Fix suspicious RCU usage warning in ip_tunnel_init_flow() 2024-10-29 11:12:25 -07:00
init cfi: fix conditions for HAVE_CFI_ICALL_NORMALIZE_INTEGERS 2024-10-13 22:23:13 +02:00
io_uring io_uring/rw: fix wrong NOWAIT check in io_rw_init_file() 2024-10-19 09:25:45 -06:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel Including fixes from netfiler, xfrm and bluetooth. 2024-10-24 16:43:50 -07:00
lib Probes fixes for v6.12-rc4(2): 2024-10-24 13:51:58 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm LoongArch: Set initial pte entry with PAGE_GLOBAL for kernel space 2024-10-21 22:11:19 +08:00
net net/sched: sch_api: fix xa_insert() error path in tcf_block_get_ext() 2024-10-29 11:45:23 -07:00
rust Driver core fix for 6.12-rc3 2024-10-13 09:10:52 -07:00
samples [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
scripts kbuild: rust: add CONFIG_RUSTC_LLVM_VERSION 2024-10-13 22:22:28 +02:00
security ipe: fallback to platform keyring also if key in trusted keyring is rejected 2024-10-18 12:14:53 -07:00
sound ALSA: hda/conexant - Use cached pin control for Node 0x1d on HP EliteOne 1000 G2 2024-10-16 10:29:57 +02:00
tools selftests: netfilter: nft_flowtable.sh: make first pass deterministic 2024-10-29 11:26:09 -07:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt ARM64: 2024-10-21 11:22:04 -07:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.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 Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap Including fixes from netfiler, xfrm and bluetooth. 2024-10-24 16:43:50 -07:00
.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 CREDITS: sort alphabetically by name 2024-10-09 12:47:19 -07:00
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 Including fixes from netfiler, xfrm and bluetooth. 2024-10-24 16:43:50 -07:00
Makefile Linux 6.12-rc4 2024-10-20 15:19:38 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -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 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.