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Filename Latest commit message Latest commit date
Florian Westphal 586892e341 netfilter: ctnetlink: fix refcount leak on table dump
[ Upstream commit de788b2e6227462b6dcd0e07474e72c089008f74 ]

There is a reference count leak in ctnetlink_dump_table():
      if (res < 0) {
                nf_conntrack_get(&ct->ct_general); // HERE
                cb->args[1] = (unsigned long)ct;
                ...

While its very unlikely, its possible that ct == last.
If this happens, then the refcount of ct was already incremented.
This 2nd increment is never undone.

This prevents the conntrack object from being released, which in turn
keeps prevents cnet->count from dropping back to 0.

This will then block the netns dismantle (or conntrack rmmod) as
nf_conntrack_cleanup_net_list() will wait forever.

This can be reproduced by running conntrack_resize.sh selftest in a loop.
It takes ~20 minutes for me on a preemptible kernel on average before
I see a runaway kworker spinning in nf_conntrack_cleanup_net_list.

One fix would to change this to:
        if (res < 0) {
		if (ct != last)
	                nf_conntrack_get(&ct->ct_general);

But this reference counting isn't needed in the first place.
We can just store a cookie value instead.

A followup patch will do the same for ctnetlink_exp_dump_table,
it looks to me as if this has the same problem and like
ctnetlink_dump_table, we only need a 'skip hint', not the actual
object so we can apply the same cookie strategy there as well.

Fixes: d205dc4079 ("[NETFILTER]: ctnetlink: fix deadlock in table dumping")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-08-28 16:21:24 +02:00
arch MIPS: mm: tlb-r4k: Uniquify TLB entries on init 2025-08-28 16:21:23 +02:00
block
certs
crypto
Documentation Documentation: ACPI: Fix parent device references 2025-08-28 16:21:23 +02:00
drivers ACPI: processor: perflib: Move problematic pr->performance check 2025-08-28 16:21:24 +02:00
fs fs: Prevent file descriptor table allocations exceeding INT_MAX 2025-08-28 16:21:23 +02:00
include io_uring: don't use int for ABI 2025-08-28 16:21:23 +02:00
init bpfilter: match bit size of bpfilter_umh to that of the kernel 2025-07-17 18:24:51 +02:00
ipc
kernel perf/core: Prevent VMA split of buffer mappings 2025-08-28 16:21:23 +02:00
lib lib: test_objagg: Set error message in check_expect_hints_stats() 2025-07-17 18:24:56 +02:00
LICENSES
mm
net netfilter: ctnetlink: fix refcount leak on table dump 2025-08-28 16:21:24 +02:00
samples samples: mei: Fix building on musl libc 2025-08-28 16:21:19 +02:00
scripts kbuild: use -MMD instead of -MD to exclude system headers from dependency 2025-07-17 18:24:51 +02:00
security
sound ALSA: usb-audio: Validate UAC3 cluster segment descriptors 2025-08-28 16:21:23 +02:00
tools perf tests bp_account: Fix leaked file descriptor 2025-08-28 16:21:20 +02:00
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
Makefile Linux 5.4.296 2025-07-17 18:25:06 +02:00
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