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Message-ID: <2025022616-CVE-2022-49194-fc80@gregkh>
Date: Wed, 26 Feb 2025 02:56:39 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49194: net: bcmgenet: Use stronger register read/writes to assure ordering
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
net: bcmgenet: Use stronger register read/writes to assure ordering
GCC12 appears to be much smarter about its dependency tracking and is
aware that the relaxed variants are just normal loads and stores and
this is causing problems like:
[ 210.074549] ------------[ cut here ]------------
[ 210.079223] NETDEV WATCHDOG: enabcm6e4ei0 (bcmgenet): transmit queue 1 timed out
[ 210.086717] WARNING: CPU: 1 PID: 0 at net/sched/sch_generic.c:529 dev_watchdog+0x234/0x240
[ 210.095044] Modules linked in: genet(E) nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat]
[ 210.146561] ACPI CPPC: PCC check channel failed for ss: 0. ret=-110
[ 210.146927] CPU: 1 PID: 0 Comm: swapper/1 Tainted: G E 5.17.0-rc7G12+ #58
[ 210.153226] CPPC Cpufreq:cppc_scale_freq_workfn: failed to read perf counters
[ 210.161349] Hardware name: Raspberry Pi Foundation Raspberry Pi 4 Model B/Raspberry Pi 4 Model B, BIOS EDK2-DEV 02/08/2022
[ 210.161353] pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 210.161358] pc : dev_watchdog+0x234/0x240
[ 210.161364] lr : dev_watchdog+0x234/0x240
[ 210.161368] sp : ffff8000080a3a40
[ 210.161370] x29: ffff8000080a3a40 x28: ffffcd425af87000 x27: ffff8000080a3b20
[ 210.205150] x26: ffffcd425aa00000 x25: 0000000000000001 x24: ffffcd425af8ec08
[ 210.212321] x23: 0000000000000100 x22: ffffcd425af87000 x21: ffff55b142688000
[ 210.219491] x20: 0000000000000001 x19: ffff55b1426884c8 x18: ffffffffffffffff
[ 210.226661] x17: 64656d6974203120 x16: 0000000000000001 x15: 6d736e617274203a
[ 210.233831] x14: 2974656e65676d63 x13: ffffcd4259c300d8 x12: ffffcd425b07d5f0
[ 210.241001] x11: 00000000ffffffff x10: ffffcd425b07d5f0 x9 : ffffcd4258bdad9c
[ 210.248171] x8 : 00000000ffffdfff x7 : 000000000000003f x6 : 0000000000000000
[ 210.255341] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000001000
[ 210.262511] x2 : 0000000000001000 x1 : 0000000000000005 x0 : 0000000000000044
[ 210.269682] Call trace:
[ 210.272133] dev_watchdog+0x234/0x240
[ 210.275811] call_timer_fn+0x3c/0x15c
[ 210.279489] __run_timers.part.0+0x288/0x310
[ 210.283777] run_timer_softirq+0x48/0x80
[ 210.287716] __do_softirq+0x128/0x360
[ 210.291392] __irq_exit_rcu+0x138/0x140
[ 210.295243] irq_exit_rcu+0x1c/0x30
[ 210.298745] el1_interrupt+0x38/0x54
[ 210.302334] el1h_64_irq_handler+0x18/0x24
[ 210.306445] el1h_64_irq+0x7c/0x80
[ 210.309857] arch_cpu_idle+0x18/0x2c
[ 210.313445] default_idle_call+0x4c/0x140
[ 210.317470] cpuidle_idle_call+0x14c/0x1a0
[ 210.321584] do_idle+0xb0/0x100
[ 210.324737] cpu_startup_entry+0x30/0x8c
[ 210.328675] secondary_start_kernel+0xe4/0x110
[ 210.333138] __secondary_switched+0x94/0x98
The assumption when these were relaxed seems to be that device memory
would be mapped non reordering, and that other constructs
(spinlocks/etc) would provide the barriers to assure that packet data
and in memory rings/queues were ordered with respect to device
register reads/writes. This itself seems a bit sketchy, but the real
problem with GCC12 is that it is moving the actual reads/writes around
at will as though they were independent operations when in truth they
are not, but the compiler can't know that. When looking at the
assembly dumps for many of these routines its possible to see very
clean, but not strictly in program order operations occurring as the
compiler would be free to do if these weren't actually register
reads/write operations.
Its possible to suppress the timeout with a liberal bit of dma_mb()'s
sprinkled around but the device still seems unable to reliably
send/receive data. A better plan is to use the safer readl/writel
everywhere.
Since this partially reverts an older commit, which notes the use of
the relaxed variants for performance reasons. I would suggest that
any performance problems with this commit are targeted at relaxing only
the performance critical code paths after assuring proper barriers.
The Linux kernel CVE team has assigned CVE-2022-49194 to this issue.
Affected and fixed versions
===========================
Issue introduced in 4.14 with commit 69d2ea9c798983c4a7157278ec84ff969d1cd8e8 and fixed in 5.10.110 with commit b26091a02093104259ca64aeca73601e56160d62
Issue introduced in 4.14 with commit 69d2ea9c798983c4a7157278ec84ff969d1cd8e8 and fixed in 5.15.33 with commit 06d836801cd82ded282aaf9e888ff9e7e4a88b91
Issue introduced in 4.14 with commit 69d2ea9c798983c4a7157278ec84ff969d1cd8e8 and fixed in 5.16.19 with commit 1d717816189fd68f9e089cf89ed1f7327d2c2e71
Issue introduced in 4.14 with commit 69d2ea9c798983c4a7157278ec84ff969d1cd8e8 and fixed in 5.17.2 with commit f49769b462f282477ca801cf648f875b1c5b59db
Issue introduced in 4.14 with commit 69d2ea9c798983c4a7157278ec84ff969d1cd8e8 and fixed in 5.18 with commit 8d3ea3d402db94b61075617e71b67459a714a502
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2022-49194
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
drivers/net/ethernet/broadcom/genet/bcmgenet.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/b26091a02093104259ca64aeca73601e56160d62
https://git.kernel.org/stable/c/06d836801cd82ded282aaf9e888ff9e7e4a88b91
https://git.kernel.org/stable/c/1d717816189fd68f9e089cf89ed1f7327d2c2e71
https://git.kernel.org/stable/c/f49769b462f282477ca801cf648f875b1c5b59db
https://git.kernel.org/stable/c/8d3ea3d402db94b61075617e71b67459a714a502
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