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From a254fe579062a9eaf97f2b81474c19b4b46ddc85 Mon Sep 17 00:00:00 2001
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From: Alex Williamson <alex.williamson@redhat.com>
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Date: Fri, 10 Apr 2015 16:33:56 +0200
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Subject: [PATCH 04/14] vfio: Fix overrun after readlink() fills buffer
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completely
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Message-id: <20150410163356.15324.47617.stgit@gimli.home>
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Patchwork-id: 64786
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O-Subject: [RHEL7.2 qemu-kvm PATCH 4/8] vfio: Fix overrun after readlink() fills buffer completely
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Bugzilla: 1210504
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: Bandan Das <bsd@redhat.com>
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From: Markus Armbruster <armbru@redhat.com>
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Upstream: 13665a2d2f675341e73618fcd7f9d36b6c68b509
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readlink() returns the number of bytes written to the buffer, and it
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doesn't write a terminating null byte. vfio_init() writes it itself.
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Overruns the buffer when readlink() filled it completely.
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Fix by treating readlink() filling the buffer completely as error,
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like we do in pci-assign.c's assign_failed_examine().
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Spotted by Coverity.
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Signed-off-by: Markus Armbruster <armbru@redhat.com>
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Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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hw/misc/vfio.c | 6 +++---
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1 file changed, 3 insertions(+), 3 deletions(-)
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diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
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index 57bc974..81e6594 100644
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--- a/hw/misc/vfio.c
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+++ b/hw/misc/vfio.c
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@@ -3767,10 +3767,10 @@ static int vfio_initfn(PCIDevice *pdev)
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strncat(path, "iommu_group", sizeof(path) - strlen(path) - 1);
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- len = readlink(path, iommu_group_path, PATH_MAX);
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- if (len <= 0) {
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+ len = readlink(path, iommu_group_path, sizeof(path));
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+ if (len <= 0 || len >= sizeof(path)) {
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error_report("vfio: error no iommu_group for device");
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- return -errno;
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+ return len < 0 ? -errno : ENAMETOOLONG;
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}
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iommu_group_path[len] = 0;
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--
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1.8.3.1
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