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