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Filename Latest commit message Latest commit date
Lion Ackermann 1e81917710 UPSTREAM: net/sched: Always pass notifications when child class becomes empty
[ Upstream commit 103406b38c600fec1fe375a77b27d87e314aea09 ]

Certain classful qdiscs may invoke their classes' dequeue handler on an
enqueue operation. This may unexpectedly empty the child qdisc and thus
make an in-flight class passive via qlen_notify(). Most qdiscs do not
expect such behaviour at this point in time and may re-activate the
class eventually anyways which will lead to a use-after-free.

The referenced fix commit attempted to fix this behavior for the HFSC
case by moving the backlog accounting around, though this turned out to
be incomplete since the parent's parent may run into the issue too.
The following reproducer demonstrates this use-after-free:

    tc qdisc add dev lo root handle 1: drr
    tc filter add dev lo parent 1: basic classid 1:1
    tc class add dev lo parent 1: classid 1:1 drr
    tc qdisc add dev lo parent 1:1 handle 2: hfsc def 1
    tc class add dev lo parent 2: classid 2:1 hfsc rt m1 8 d 1 m2 0
    tc qdisc add dev lo parent 2:1 handle 3: netem
    tc qdisc add dev lo parent 3:1 handle 4: blackhole

    echo 1 | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888
    tc class delete dev lo classid 1:1
    echo 1 | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888

Since backlog accounting issues leading to a use-after-frees on stale
class pointers is a recurring pattern at this point, this patch takes
a different approach. Instead of trying to fix the accounting, the patch
ensures that qdisc_tree_reduce_backlog always calls qlen_notify when
the child qdisc is empty. This solves the problem because deletion of
qdiscs always involves a call to qdisc_reset() and / or
qdisc_purge_queue() which ultimately resets its qlen to 0 thus causing
the following qdisc_tree_reduce_backlog() to report to the parent. Note
that this may call qlen_notify on passive classes multiple times. This
is not a problem after the recent patch series that made all the
classful qdiscs qlen_notify() handlers idempotent.

Bug: 431676976
Fixes: 3f981138109f ("sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue()")
Signed-off-by: Lion Ackermann <nnamrec@gmail.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit e9921b57dca05ac5f4fa1fa8e993d4f0ee52e2b7)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I2eb242c0279efc5c5e31e63f7fb12a3f4d5f3e1d
2025-08-05 16:23:04 +01:00
android ANDROID: GKI: Update symbol list for Zebra 2025-06-30 05:23:36 -07:00
arch Merge tag 'android11-5.4.295_r00' into android11-5.4 2025-07-26 00:43:02 -07:00
block This is the 5.4.292 stable release 2025-04-11 08:16:05 +00:00
certs
crypto This is the 5.4.294 stable release 2025-06-05 07:11:21 +00:00
Documentation This is the 5.4.295 stable release 2025-06-30 08:05:33 +00:00
drivers This is the 5.4.295 stable release 2025-06-30 08:05:33 +00:00
fs This is the 5.4.295 stable release 2025-06-30 08:05:33 +00:00
include This is the 5.4.295 stable release 2025-06-30 08:05:33 +00:00
init This is the 5.4.293 stable release 2025-05-05 12:47:34 +00:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:02:52 +01:00
kernel ANDROID: bpf: do not fail to load if log is full 2025-07-29 07:38:45 +00:00
lib This is the 5.4.294 stable release 2025-06-05 07:11:21 +00:00
LICENSES
mm This is the 5.4.295 stable release 2025-06-30 08:05:33 +00:00
net UPSTREAM: net/sched: Always pass notifications when child class becomes empty 2025-08-05 16:23:04 +01:00
samples Merge 5.4.287 into android11-5.4-lts 2024-12-16 10:50:16 +00:00
scripts This is the 5.4.294 stable release 2025-06-05 07:11:21 +00:00
security This is the 5.4.295 stable release 2025-06-30 08:05:33 +00:00
sound This is the 5.4.295 stable release 2025-06-30 08:05:33 +00:00
tools This is the 5.4.295 stable release 2025-06-30 08:05:33 +00:00
usr
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
build.config.aarch64
build.config.allmodconfig
build.config.allmodconfig.aarch64
build.config.allmodconfig.arm
build.config.allmodconfig.x86_64
build.config.arm
build.config.common
build.config.db845c ANDROID: db845c: Enable device tree overlay support 2024-01-13 10:38:25 +05:30
build.config.gki
build.config.gki-debug.aarch64
build.config.gki-debug.x86_64
build.config.gki.aarch64 ANDROID: GKI: add Trimble symbol list 2025-01-16 06:41:15 -08:00
build.config.gki.x86_64
build.config.gki_kasan
build.config.gki_kasan.aarch64
build.config.gki_kasan.x86_64
build.config.gki_kprobes
build.config.gki_kprobes.aarch64
build.config.gki_kprobes.x86_64
build.config.hikey960
build.config.x86_64
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS This is the 5.4.295 stable release 2025-06-30 08:05:33 +00:00
Makefile This is the 5.4.295 stable release 2025-06-30 08:05:33 +00:00
OWNERS ANDROID: Use GKI Dr. No OWNERS file 2023-12-04 13:28:17 +00:00
README
README.md

How do I submit patches to Android Common Kernels

  1. BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.

  2. LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.

Common Kernel patch requirements

  • All patches must conform to the Linux kernel coding standards and pass script/checkpatch.pl
  • Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
  • If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch: UPSTREAM:, BACKPORT:, FROMGIT:, FROMLIST:, or ANDROID:.
  • All patches must have a Change-Id: tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html)
  • If an Android bug has been assigned, there must be a Bug: tag.
  • All patches must have a Signed-off-by: tag by the author and the submitter

Additional requirements are listed below based on patch type

Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:

  • If the patch is a cherry-pick from Linux mainline with no changes at all
    • tag the patch subject with UPSTREAM:.
    • add upstream commit information with a (cherry-picked from ...) line
    • Example:
      • if the upstream commit message is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
    - then Joe Smith would upload the patch for the common kernel as
        UPSTREAM: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry-picked from c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch requires any changes from the upstream version, tag the patch with BACKPORT: instead of UPSTREAM:.
    • use the same tags as UPSTREAM:
    • add comments about the changes under the (cherry-picked from ...) line
    • Example:
        BACKPORT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry-picked from c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        [ Resolved minor conflict in drivers/foo/bar.c ]
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for other backports: FROMGIT:, FROMLIST:,

  • If the patch has been merged into an upstream maintainer tree, but has not yet been merged into Linux mainline
    • tag the patch subject with FROMGIT:
    • add info on where the patch came from as (cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't use linux-next for example).
    • if changes were required, use BACKPORT: FROMGIT:
    • Example:
      • if the commit message in the maintainer tree is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
    - then Joe Smith would upload the patch for the common kernel as
        FROMGIT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        (cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
         https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch has been submitted to LKML, but not accepted into any maintainer tree
    • tag the patch subject with FROMLIST:
    • add a Link: tag with a link to the submittal on lore.kernel.org
    • if changes were required, use BACKPORT: FROMLIST:
    • Example:
        FROMLIST: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for Android-specific patches: ANDROID:

  • If the patch is fixing a bug to Android-specific code
    • tag the patch subject with ANDROID:
    • add a Fixes: tag that cites the patch with the bug
    • Example:
        ANDROID: fix android-specific bug in foobar.c

        This is the detailed description of the important fix

        Fixes: 1234abcd2468 ("foobar: add cool feature")
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch is a new feature
    • tag the patch subject with ANDROID:
    • add a Bug: tag with the Android bug (required for android-specific features)