[Qemu-devel] [PULL 14/43] spapr: fix out of bounds write in spapr_populate_drmem_v2

David Gibson posted 43 patches 72 weeks ago
Maintainers: "Hervé Poussineau" <hpoussin@reactos.org>, "Michael S. Tsirkin" <mst@redhat.com>, "Cédric Le Goater" <clg@kaod.org>, Igor Mammedov <imammedo@redhat.com>, Gerd Hoffmann <kraxel@redhat.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Dmitry Fleytman <dmitry.fleytman@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>, Halil Pasic <pasic@linux.ibm.com>, Fam Zheng <fam@euphon.net>, David Gibson <david@gibson.dropbear.id.au>, Amit Shah <amit@kernel.org>, Collin Walling <walling@linux.ibm.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Richard Henderson <rth@twiddle.net>, David Hildenbrand <david@redhat.com>, Cornelia Huck <cohuck@redhat.com>

[Qemu-devel] [PULL 14/43] spapr: fix out of bounds write in spapr_populate_drmem_v2

Posted by David Gibson 72 weeks ago
From: Fabiano Rosas <farosas@linux.ibm.com>

buf_len is uint8_t which is not large enough to hold the result of:

  nr_entries * sizeof(struct sPAPRDrconfCellV2) + sizeof(uint32_t);

for a nr_entries greater than 10.

This causes the allocated buffer 'int_buf' to be smaller than expected
and we eventually overwrite some of glibc's control structures (see
"chunk" in https://sourceware.org/glibc/wiki/MallocInternals)

The following error is seen while trying to free int_buf:

  "free(): invalid next size (fast)"

Fixes: a324d6f166 "spapr: Support ibm,dynamic-memory-v2 property"
Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Message-Id: <20190213172926.21740-1-farosas@linux.ibm.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
 hw/ppc/spapr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 850cfe28c4..abf9ebce59 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -687,14 +687,14 @@ static int spapr_populate_drmem_v2(sPAPRMachineState *spapr, void *fdt,
                                    int offset, MemoryDeviceInfoList *dimms)
     MachineState *machine = MACHINE(spapr);
-    uint8_t *int_buf, *cur_index, buf_len;
+    uint8_t *int_buf, *cur_index;
     int ret;
     uint64_t lmb_size = SPAPR_MEMORY_BLOCK_SIZE;
     uint64_t addr, cur_addr, size;
     uint32_t nr_boot_lmbs = (machine->device_memory->base / lmb_size);
     uint64_t mem_end = machine->device_memory->base +
-    uint32_t node, nr_entries = 0;
+    uint32_t node, buf_len, nr_entries = 0;
     sPAPRDRConnector *drc;
     DrconfCellQueue *elem, *next;
     MemoryDeviceInfoList *info;