stable inclusion from stable-v6.1.98 commit c550679d604798d9fed8a5b2bb5693448a25407c category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAHJIE CVE: CVE-2024-42230

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit 21a741eb75f80397e5f7d3739e24d7d75e619011 upstream.

kexec on pseries disables AIL (reloc_on_exc), required for scv instruction support, before other CPUs have been shut down. This means they can execute scv instructions after AIL is disabled, which causes an interrupt at an unexpected entry location that crashes the kernel.

Change the kexec sequence to disable AIL after other CPUs have been brought down.

As a refresher, the real-mode scv interrupt vector is 0x17000, and the fixed-location head code probably couldn't easily deal with implementing such high addresses so it was just decided not to support that interrupt at all.

Fixes: 7fa95f9adaee ("powerpc/64s: system call support for scv/rfscv instructions") Cc: stable@vger.kernel.org # v5.9+ Reported-by: Sourabh Jain sourabhjain@linux.ibm.com Closes: https://lore.kernel.org/3b4b2943-49ad-4619-b195-bc416f1d1409@linux.ibm.com Signed-off-by: Nicholas Piggin npiggin@gmail.com Tested-by: Gautam Menghani gautam@linux.ibm.com Tested-by: Sourabh Jain sourabhjain@linux.ibm.com Link: https://msgid.link/20240625134047.298759-1-npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

Conflicts: arch/powerpc/kexec/core_64.c arch/powerpc/platforms/pseries/kexec.c arch/powerpc/platforms/pseries/pseries.h arch/powerpc/platforms/pseries/setup.c [Fix context conflicts because the content of c550679d604798d9fed8a5b2bb5693448a25407c is based on commit 2ab2d5794f14c08676690bf0859f16cc768bb3a4, 2ab2d5794f14c08676690bf0859f16cc768bb3a4 moves function "pSeries_machine_kexec" from "arch/powerpc/platforms/pseries/setup.c" to "arch/powerpc/platforms/pseries/kexec.c". But 2ab2d5794f14c08676690bf0859f16cc768bb3a4 is not incorporated in this version] Signed-off-by: Lin RuiFeng linruifeng4@huawei.com --- arch/powerpc/kexec/core_64.c | 11 +++++++++++ arch/powerpc/platforms/pseries/setup.c | 11 ----------- 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/kexec/core_64.c b/arch/powerpc/kexec/core_64.c index 8a449b2d8715..083e90d69601 100644 --- a/arch/powerpc/kexec/core_64.c +++ b/arch/powerpc/kexec/core_64.c @@ -25,6 +25,7 @@ #include <asm/paca.h> #include <asm/mmu.h> #include <asm/sections.h> /* _end */ +#include <asm/setup.h> #include <asm/prom.h> #include <asm/smp.h> #include <asm/hw_breakpoint.h> @@ -313,6 +314,16 @@ void default_machine_kexec(struct kimage *image) if (!kdump_in_progress()) kexec_prepare_cpus();

+ #ifdef CONFIG_PPC_PSERIES + /* + * This must be done after other CPUs have shut down, otherwise they + * could execute the 'scv' instruction, which is not supported with + * reloc disabled (see configure_exceptions()). + */ + if (firmware_has_feature(FW_FEATURE_SET_MODE)) + pseries_disable_reloc_on_exc(); + #endif + printk("kexec: Starting switchover sequence.\n");

/* switch to a staticly allocated stack. Based on irq stack code. diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 1ca13369f31c..0f1c8d43f9ef 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -409,16 +409,6 @@ void pseries_disable_reloc_on_exc(void) } EXPORT_SYMBOL(pseries_disable_reloc_on_exc);

-#ifdef CONFIG_KEXEC_CORE -static void pSeries_machine_kexec(struct kimage *image) -{ - if (firmware_has_feature(FW_FEATURE_SET_MODE)) - pseries_disable_reloc_on_exc(); - - default_machine_kexec(image); -} -#endif - #ifdef __LITTLE_ENDIAN__ void pseries_big_endian_exceptions(void) { @@ -1071,7 +1061,6 @@ define_machine(pseries) { .machine_check_early = pseries_machine_check_realmode, .machine_check_exception = pSeries_machine_check_exception, #ifdef CONFIG_KEXEC_CORE - .machine_kexec = pSeries_machine_kexec, .kexec_cpu_down = pseries_kexec_cpu_down, #endif #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE