[PULL 06/15] s390x/ipl: validate num_comp against iplb length before iterating

From: Joshua Daley <[email protected]>

In ipl_valid_pv_components(), the upper bound of the for loop,
ipib_pv->num_comp, is read from guest memory. Before iterating, verify
that its value will not cause a read beyond the end of the
IplParameterBlock.

Fixes: c3347ed0d2ee42a7 ("s390x: protvirt: Support unpack facility")
Cc: [email protected]
Signed-off-by: Joshua Daley <[email protected]>
Reviewed-by: Christian Borntraeger <[email protected]>
Reviewed-by: Matthew Rosato <[email protected]>
Reviewed-by: Eric Farman <[email protected]>
Link: https://lore.kernel.org/qemu-devel/[email protected]
[[email protected]: Added qemu-stable]
Signed-off-by: Eric Farman <[email protected]>
---
 hw/s390x/ipl.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
index fac30763df..ef9c063d90 100644
--- a/hw/s390x/ipl.h
+++ b/hw/s390x/ipl.h
@@ -124,6 +124,12 @@ static inline bool ipl_valid_pv_components(IplParameterBlock *iplb)
         return false;
     }
 
+    if (offsetof(IplParameterBlock, pv.components) +
+        ipib_pv->num_comp * sizeof(IPLBlockPVComp) >
+        be32_to_cpu(iplb->len)) {
+        return false;
+    }
+
     for (i = 0; i < ipib_pv->num_comp; i++) {
         /* Addr must be 4k aligned */
         if (ipib_pv->components[i].addr & ~TARGET_PAGE_MASK) {
-- 
2.55.0