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envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=148.163.156.1; envelope-from=rathc@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @ibm.com) X-ZM-MESSAGEID: 1789676913553158500 Content-Type: text/plain; charset="utf-8" vmstate_rx_buffer_pool restores count and bufsize as raw int32 values with no bounds checking. A crafted migration stream can set count to any int32 value. spapr_vlan_get_rx_bd_from_pool() then passes the count > 0 guard, decrements count, and uses the result as an array index into bds[], a 4096-entry fixed heap allocation: dev->rx_pool[pool]->count--; bd =3D dev->rx_pool[pool]->bds[dev->rx_pool[pool]->count]; /* OOB rea= d */ dev->rx_pool[pool]->bds[dev->rx_pool[pool]->count] =3D 0; /* OOB wri= te */ With count =3D=3D INT32_MAX this lands ~17 GiB past the start of a 32 KiB heap object. Additionally, a negative bufsize silently compares as a huge value when widened to size_t, defeating the bufsize >=3D size + 8 pool-selection guard. The hypercall path (spapr_vlan_add_rxbuf_to_pool) already enforces 0 <=3D count < RX_POOL_MAX_BDS; add a post_load hook to vmstate_rx_buffer_pool that rejects any stream violating the same invariant, failing the incoming migration. Closes: https://gitlab.com/qemu-project/qemu/-/work_items/4147 Reported-by: Lazymio Signed-off-by: Chinmay Rath --- hw/net/spapr_llan.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/hw/net/spapr_llan.c b/hw/net/spapr_llan.c index 550848307d..a5b8906849 100644 --- a/hw/net/spapr_llan.c +++ b/hw/net/spapr_llan.c @@ -800,11 +800,29 @@ static bool spapr_vlan_rx_buffer_pools_needed(void *o= paque) return (dev->compat_flags & SPAPRVLAN_FLAG_RX_BUF_POOLS) !=3D 0; } =20 +static int spapr_vlan_rx_buffer_pool_post_load(void *opaque, int version_i= d) +{ + RxBufPool *rxp =3D opaque; + + if (rxp->count < 0 || rxp->count > RX_POOL_MAX_BDS) { + return -EINVAL; + } + /* + * bufsize is compared against a size_t in spapr_vlan_get_rx_bd_from_p= ool(), + * so a negative value would compare as huge. + */ + if (rxp->bufsize < 0) { + return -EINVAL; + } + return 0; +} + static const VMStateDescription vmstate_rx_buffer_pool =3D { .name =3D "spapr_llan/rx_buffer_pool", .version_id =3D 1, .minimum_version_id =3D 1, .needed =3D spapr_vlan_rx_buffer_pools_needed, + .post_load =3D spapr_vlan_rx_buffer_pool_post_load, .fields =3D (const VMStateField[]) { VMSTATE_INT32(bufsize, RxBufPool), VMSTATE_INT32(count, RxBufPool), --=20 2.55.0