CVE-2021-46925

published 2024-02-27

CVE-2021-46925: In the Linux kernel, the following vulnerability has been resolved: net/smc: fix kernel panic caused by race of smc_sock A crash occurs when…

Priority P4 16 medium 4.7 CVSS 3.1

AV L AC H PR L UI N S U C N I N A H

In the Linux kernel, the following vulnerability has been resolved:

net/smc: fix kernel panic caused by race of smc_sock

A crash occurs when smc_cdc_tx_handler() tries to access smc_sock
but smc_release() has already freed it.

[ 4570.695099] BUG: unable to handle page fault for address: 000000002eae9e88
[ 4570.696048] #PF: supervisor write access in kernel mode
[ 4570.696728] #PF: error_code(0x0002) - not-present page
[ 4570.697401] PGD 0 P4D 0
[ 4570.697716] Oops: 0002 [#1] PREEMPT SMP NOPTI
[ 4570.698228] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.16.0-rc4+ #111
[ 4570.699013] Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 8c24b4c 04/0
[ 4570.699933] RIP: 0010:_raw_spin_lock+0x1a/0x30

[ 4570.711446] Call Trace:
[ 4570.711746]
[ 4570.711992] smc_cdc_tx_handler+0x41/0xc0
[ 4570.712470] smc_wr_tx_tasklet_fn+0x213/0x560
[ 4570.712981] ? smc_cdc_tx_dismisser+0x10/0x10
[ 4570.713489] tasklet_action_common.isra.17+0x66/0x140
[ 4570.714083] __do_softirq+0x123/0x2f4
[ 4570.714521] irq_exit_rcu+0xc4/0xf0
[ 4570.714934] common_interrupt+0xba/0xe0

Though smc_cdc_tx_handler() checked the existence of smc connection,
smc_release() may have already dismissed and released the smc socket
before smc_cdc_tx_handler() further visits it.

smc_cdc_tx_handler() |smc_release()
if (!conn) |
|
|smc_cdc_tx_dismiss_slots()
| smc_cdc_tx_dismisser()
|
|sock_put(&smc->sk) sk) (panic) |

To make sure we won't receive any CDC messages after we free the
smc_sock, add a refcount on the smc_connection for inflight CDC
message(posted to the QP but haven't received related CQE), and
don't release the smc_connection until all the inflight CDC messages
haven been done, for both success or failed ones.

Using refcount on CDC messages brings another problem: when the link
is going to be destroyed, smcr_link_clear() will reset the QP, which
then remove all the pending CQEs related to the QP in the CQ. To make
sure all the CQEs will always come back so the refcount on the
smc_connection can alwa

Affected

11 ranges

Vendor	Product	Version range	Fixed in
debian	linux	< linux 5.15.15-1 (bookworm)	linux 5.15.15-1 (bookworm)
linux	linux	—	—
linux	linux	>= 5f08318f617b05b6ee389d8bd174c7af921ebf19 < e8a5988a85c719ce7205cb00dcf0716dcf611332	e8a5988a85c719ce7205cb00dcf0716dcf611332
linux	linux	>= 5f08318f617b05b6ee389d8bd174c7af921ebf19 < b85f751d71ae8e2a15e9bda98852ea9af35282eb	b85f751d71ae8e2a15e9bda98852ea9af35282eb
linux	linux	>= 5f08318f617b05b6ee389d8bd174c7af921ebf19 < 349d43127dac00c15231e8ffbcaabd70f7b0e544	349d43127dac00c15231e8ffbcaabd70f7b0e544
linux	linux_kernel	>= 0 < 5.10.92-1	5.10.92-1
linux	linux_kernel	>= 0 < 5.15.15-1	5.15.15-1
linux	linux_kernel	>= 0 < 5.15.15-1	5.15.15-1
linux	linux_kernel	>= 0 < 5.15.15-1	5.15.15-1
linux	linux_kernel	>= 4.11.0 < 5.10.90	5.10.90
linux	linux_kernel	>= 5.11.0 < 5.15.13	5.15.13

CVSS provenance

nvd v3.1 4.7 MEDIUM CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

osv 4.7 MEDIUM

vendor_debian 4.7 MEDIUM

vendor_redhat 4.7 MEDIUM

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