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KVM: arm64: Prevent kmemleak from accessing pKVM memory
Commita7259df767
("memblock: make memblock_find_in_range method private") changed the API using which memory is reserved for the pKVM hypervisor. However, memblock_phys_alloc() differs from the original API in terms of kmemleak semantics -- the old one didn't report the reserved regions to kmemleak while the new one does. Unfortunately, when protected KVM is enabled, all kernel accesses to pKVM-private memory result in a fatal exception, which can now happen because of kmemleak scans: $ echo scan > /sys/kernel/debug/kmemleak [ 34.991354] kvm [304]: nVHE hyp BUG at: [<ffff800008fa3750>] __kvm_nvhe_handle_host_mem_abort+0x270/0x290! [ 34.991580] kvm [304]: Hyp Offset: 0xfffe8be807e00000 [ 34.991813] Kernel panic - not syncing: HYP panic: [ 34.991813] PS:600003c9 PC:0000f418011a3750 ESR:00000000f2000800 [ 34.991813] FAR:ffff000439200000 HPFAR:0000000004792000 PAR:0000000000000000 [ 34.991813] VCPU:0000000000000000 [ 34.993660] CPU: 0 PID: 304 Comm: bash Not tainted 5.19.0-rc2 #102 [ 34.994059] Hardware name: linux,dummy-virt (DT) [ 34.994452] Call trace: [ 34.994641] dump_backtrace.part.0+0xcc/0xe0 [ 34.994932] show_stack+0x18/0x6c [ 34.995094] dump_stack_lvl+0x68/0x84 [ 34.995276] dump_stack+0x18/0x34 [ 34.995484] panic+0x16c/0x354 [ 34.995673] __hyp_pgtable_total_pages+0x0/0x60 [ 34.995933] scan_block+0x74/0x12c [ 34.996129] scan_gray_list+0xd8/0x19c [ 34.996332] kmemleak_scan+0x2c8/0x580 [ 34.996535] kmemleak_write+0x340/0x4a0 [ 34.996744] full_proxy_write+0x60/0xbc [ 34.996967] vfs_write+0xc4/0x2b0 [ 34.997136] ksys_write+0x68/0xf4 [ 34.997311] __arm64_sys_write+0x20/0x2c [ 34.997532] invoke_syscall+0x48/0x114 [ 34.997779] el0_svc_common.constprop.0+0x44/0xec [ 34.998029] do_el0_svc+0x2c/0xc0 [ 34.998205] el0_svc+0x2c/0x84 [ 34.998421] el0t_64_sync_handler+0xf4/0x100 [ 34.998653] el0t_64_sync+0x18c/0x190 [ 34.999252] SMP: stopping secondary CPUs [ 35.000034] Kernel Offset: disabled [ 35.000261] CPU features: 0x800,00007831,00001086 [ 35.000642] Memory Limit: none [ 35.001329] ---[ end Kernel panic - not syncing: HYP panic: [ 35.001329] PS:600003c9 PC:0000f418011a3750 ESR:00000000f2000800 [ 35.001329] FAR:ffff000439200000 HPFAR:0000000004792000 PAR:0000000000000000 [ 35.001329] VCPU:0000000000000000 ]--- Fix this by explicitly excluding the hypervisor's memory pool from kmemleak like we already do for the hyp BSS. Cc: Mike Rapoport <rppt@kernel.org> Fixes:a7259df767
("memblock: make memblock_find_in_range method private") Signed-off-by: Quentin Perret <qperret@google.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20220616161135.3997786-1-qperret@google.com
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@ -2112,11 +2112,11 @@ static int finalize_hyp_mode(void)
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return 0;
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/*
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* Exclude HYP BSS from kmemleak so that it doesn't get peeked
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* at, which would end badly once the section is inaccessible.
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* None of other sections should ever be introspected.
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* Exclude HYP sections from kmemleak so that they don't get peeked
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* at, which would end badly once inaccessible.
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*/
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kmemleak_free_part(__hyp_bss_start, __hyp_bss_end - __hyp_bss_start);
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kmemleak_free_part(__va(hyp_mem_base), hyp_mem_size);
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return pkvm_drop_host_privileges();
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}
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