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From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: linuxppc-dev@lists.ozlabs.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>, kvm-ppc@vger.kernel.org
Subject: [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots
Date: Wed,  1 Sep 2021 18:45:12 +1000	[thread overview]
Message-ID: <20210901084512.1658628-1-aik@ozlabs.ru> (raw)

The userspace can trigger "vmalloc size %lu allocation failure: exceeds
total pages" via the KVM_SET_USER_MEMORY_REGION ioctl.

This silences the warning by checking the limit before calling vzalloc()
and returns ENOMEM if failed.

This does not call underlying valloc helpers as __vmalloc_node() is only
exported when CONFIG_TEST_VMALLOC_MODULE and __vmalloc_node_range() is not
exported at all.

Spotted by syzkaller.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/kvm/book3s_hv.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 474c0cfde384..a59f1cccbcf9 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4830,8 +4830,12 @@ static int kvmppc_core_prepare_memory_region_hv(struct kvm *kvm,
 	unsigned long npages = mem->memory_size >> PAGE_SHIFT;
 
 	if (change == KVM_MR_CREATE) {
-		slot->arch.rmap = vzalloc(array_size(npages,
-					  sizeof(*slot->arch.rmap)));
+		unsigned long cb = array_size(npages, sizeof(*slot->arch.rmap));
+
+		if ((cb >> PAGE_SHIFT) > totalram_pages())
+			return -ENOMEM;
+
+		slot->arch.rmap = vzalloc(cb);
 		if (!slot->arch.rmap)
 			return -ENOMEM;
 	}
-- 
2.30.2


WARNING: multiple messages have this Message-ID (diff)
From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: linuxppc-dev@lists.ozlabs.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>, kvm-ppc@vger.kernel.org
Subject: [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots
Date: Wed, 01 Sep 2021 08:45:12 +0000	[thread overview]
Message-ID: <20210901084512.1658628-1-aik@ozlabs.ru> (raw)

The userspace can trigger "vmalloc size %lu allocation failure: exceeds
total pages" via the KVM_SET_USER_MEMORY_REGION ioctl.

This silences the warning by checking the limit before calling vzalloc()
and returns ENOMEM if failed.

This does not call underlying valloc helpers as __vmalloc_node() is only
exported when CONFIG_TEST_VMALLOC_MODULE and __vmalloc_node_range() is not
exported at all.

Spotted by syzkaller.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/kvm/book3s_hv.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 474c0cfde384..a59f1cccbcf9 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4830,8 +4830,12 @@ static int kvmppc_core_prepare_memory_region_hv(struct kvm *kvm,
 	unsigned long npages = mem->memory_size >> PAGE_SHIFT;
 
 	if (change = KVM_MR_CREATE) {
-		slot->arch.rmap = vzalloc(array_size(npages,
-					  sizeof(*slot->arch.rmap)));
+		unsigned long cb = array_size(npages, sizeof(*slot->arch.rmap));
+
+		if ((cb >> PAGE_SHIFT) > totalram_pages())
+			return -ENOMEM;
+
+		slot->arch.rmap = vzalloc(cb);
 		if (!slot->arch.rmap)
 			return -ENOMEM;
 	}
-- 
2.30.2

             reply	other threads:[~2021-09-01  8:46 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-01  8:45 Alexey Kardashevskiy [this message]
2021-09-01  8:45 ` [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots Alexey Kardashevskiy
2021-09-01 14:59 ` Fabiano Rosas
2021-09-01 14:59   ` Fabiano Rosas
2021-09-02  4:25   ` Alexey Kardashevskiy
2021-09-02  4:25     ` Alexey Kardashevskiy
2021-09-02 13:08     ` Fabiano Rosas
2021-09-02 13:08       ` Fabiano Rosas
2021-09-02 13:23       ` David Laight
2021-09-02 13:23         ` David Laight
2021-12-15  0:40 ` Michael Ellerman
2021-12-15  0:40   ` Michael Ellerman
2021-09-01  8:45 [PATCH kernel] KVM: PPC: Book3S: Suppress failed alloc warning in H_COPY_TOFROM_GUEST Alexey Kardashevskiy
2021-09-01  8:45 ` Alexey Kardashevskiy
2021-09-01 14:45 ` Fabiano Rosas
2021-09-01 14:45   ` Fabiano Rosas
2021-12-15  0:40 ` Michael Ellerman
2021-12-15  0:40   ` Michael Ellerman

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