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

net/smc: Transitional solution for clcsock race issue

We encountered a crash in smc_setsockopt() and it is caused by accessing smc->clcsock after clcsock was released.

BUG: kernel NULL pointer dereference, address: 0000000000000020 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 1 PID: 50309 Comm: nginx Kdump: loaded Tainted: G E 5.16.0-rc4+ #53 RIP: 0010:smc_setsockopt+0x59/0x280 [smc] Call Trace: <TASK> __sys_setsockopt+0xfc/0x190 __x64_sys_setsockopt+0x20/0x30 do_syscall_64+0x34/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f16ba83918e </TASK>

This patch tries to fix it by holding clcsock_release_lock and checking whether clcsock has already been released before access.

In case that a crash of the same reason happens in smc_getsockopt() or smc_switch_to_fallback(), this patch also checkes smc->clcsock in them too. And the caller of smc_switch_to_fallback() will identify whether fallback succeeds according to the return value.

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

net/smc: Transitional solution for clcsock race issue

We encountered a crash in smc_setsockopt() and it is caused by accessing smc->clcsock after clcsock was released.

BUG: kernel NULL pointer dereference, address: 0000000000000020 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 1 PID: 50309 Comm: nginx Kdump: loaded Tainted: G E 5.16.0-rc4+ #53 RIP: 0010:smc_setsockopt+0x59/0x280 [smc] Call Trace: <TASK> __sys_setsockopt+0xfc/0x190 __x64_sys_setsockopt+0x20/0x30 do_syscall_64+0x34/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f16ba83918e </TASK>

This patch tries to fix it by holding clcsock_release_lock and checking whether clcsock has already been released before access.

In case that a crash of the same reason happens in smc_getsockopt() or smc_switch_to_fallback(), this patch also checkes smc->clcsock in them too. And the caller of smc_switch_to_fallback() will identify whether fallback succeeds according to the return value.

Security update for the Linux Kernel

Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:Pro:18.04:LTS: linux-aws-5.4, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:Pro:18.04:LTS: linux-azure-5.4, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3 and 84 more

In the Linux kernel, the following vulnerability has been resolved: net/smc: Transitional solution for clcsock race issue We encountered a crash in smc_setsockopt() and it is caused by accessing smc->clcsock after clcsock was released. BUG: kernel NULL pointer dereference, address: 0000000000000020 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 1 PID: 50309 Comm: nginx Kdump: loaded Tainted: G E 5.16.0-rc4+ #53 RIP: 0010:smc_setsockopt+0x59/0x280 [smc] Call Trace: <TASK> __sys_setsockopt+0xfc/0x190 __x64_sys_setsockopt+0x20/0x30 do_syscall_64+0x34/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f16ba83918e </TASK> This patch tries to fix it by holding clcsock_release_lock and checking whether clcsock has already been released before access. In case that a crash of the same reason happens in smc_getsockopt() or smc_switch_to_fallback(), this patch also checkes smc->clcsock in them too. And the caller of smc_switch_to_fallback() will identify whether fallback succeeds according to the return value.

Ein lokaler Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.