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qemu-kvm: Work around borken MSR_GET_INDEX_LIST

PATCH Applied Jan Kiszka 2 participants 2 messages Jul 2, 2009 – Jul 6, 2009 KVM

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Jan Kiszka

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#0 lore raw

PATCH 1/1 qemu-kvm: Work around borken MSR_GET_INDEX_LIST

Allocate enough memory for KVM_GET_MSR_INDEX_LIST as older kernels shot far beyond their limits, corrupting user space memory.

Signed-off-by Jan Kiszka <[email protected]>

---

 qemu-kvm-x86.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
qemu-kvm-x86.c +4 -1
index d6735c1..e528acb 100644
@@ -349,7 +349,10 @@ struct kvm_msr_list *kvm_get_msr_list(kvm_context_t kvm)
 	r = ioctl(kvm->fd, KVM_GET_MSR_INDEX_LIST, &sizer);
 	if (r == -1 && errno != E2BIG)
 		return NULL;
-	msrs = malloc(sizeof *msrs + sizer.nmsrs * sizeof *msrs->indices);
+	/* Old kernel modules had a bug and could write beyond the provided
+	   memory. Allocate at least a safe amount of 1K. */
+	msrs = malloc(MAX(1024, sizeof(*msrs) +
+				sizer.nmsrs * sizeof(*msrs->indices)));
 	if (!msrs) {
 		errno = ENOMEM;
 		return NULL;
Applied
#1 lore raw
Quoted 3 lines · Jan Kiszka

Allocate enough memory for KVM_GET_MSR_INDEX_LIST as older kernels shot far beyond their limits, corrupting user space memory.

Applied, thanks.

Signature · 1 line
error compiling committee.c: too many arguments to function