On Mon, 2023-10-23 at 16:14 -0700, Si-Wei Liu wrote: > As subject. There's a vhost_vdpa_reset() done earlier before > vhost_dev is initialized via vhost_dev_init(), ending up with > NULL pointer dereference. Fix is to check if vqs is initialized > before checking backend features and resetting the device. > > BUG: kernel NULL pointer dereference, address: 0000000000000000 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 0 P4D 0 > Oops: 0000 [#1] SMP > CPU: 3 PID: 1727 Comm: qemu-system-x86 Not tainted 6.6.0-rc6+ #2 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel- > a4aeb02-prebuilt.qemu.org 04/01/2014 > RIP: 0010:_compat_vdpa_reset+0x47/0xc0 [vhost_vdpa] > Code: c7 c7 fb 12 56 a0 4c 8d a5 b8 02 00 00 48 89 ea e8 7e b8 c4 > 48 89 ee 48 c7 c7 19 13 56 a0 4c 8b ad b0 02 00 00 <48> 8b 00 49 > 00 48 8b 80 88 45 00 00 48 c1 e8 08 48 > RSP: 0018:ffff8881063c3c38 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: ffff8881074eb800 RCX: 0000000000000000 > RDX: 0000000000000000 RSI: ffff888103ab4000 RDI: ffffffffa0561319 > RBP: ffff888103ab4000 R08: 00000000ffffdfff R09: 0000000000000001 > R10: 0000000000000003 R11: ffff88887fecbac0 R12: ffff888103ab42b8 > R13: ffff888106dbe850 R14: 0000000000000003 R15: ffff8881074ebc18 > FS: 00007f02fba6ef00(0000) GS:ffff88885f8c0000(0000) > knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000000 CR3: 00000001325e5003 CR4: 0000000000372ea0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > ? __die+0x1f/0x60 > ? page_fault_oops+0x14c/0x3b0 > ? exc_page_fault+0x74/0x140 > ? asm_exc_page_fault+0x22/0x30 > ? _compat_vdpa_reset+0x47/0xc0 [vhost_vdpa] > ? _compat_vdpa_reset+0x32/0xc0 [vhost_vdpa] > vhost_vdpa_open+0x55/0x270 [vhost_vdpa] > ? sb_init_dio_done_wq+0x50/0x50 > chrdev_open+0xc0/0x210 > ? __unregister_chrdev+0x50/0x50 > do_dentry_open+0x1fc/0x4f0 > path_openat+0xc2d/0xf20 > do_filp_open+0xb4/0x160 > ? kmem_cache_alloc+0x3c/0x490 > do_sys_openat2+0x8d/0xc0 > __x64_sys_openat+0x6a/0xa0 > do_syscall_64+0x3c/0x80 > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > Fixes: 10cbf8dfaf93 ("vhost-vdpa: clean iotlb map during reset for older > userspace") > Reported-by: Dragos Tatulea <dtatulea@xxxxxxxxxx> This works, thanks for the quick response. Tested-by: Dragos Tatulea <dtatulea@xxxxxxxxxx> > Closes: > https://lore.kernel.org/all/b4913f84-8b52-4d28-af51-8573dc361f82@xxxxxxxxxx/ > Signed-off-by: Si-Wei Liu <si-wei.liu@xxxxxxxxxx> > --- > drivers/vhost/vdpa.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > index 9ce40003793b..9a2343c45df0 100644 > --- a/drivers/vhost/vdpa.c > +++ b/drivers/vhost/vdpa.c > @@ -232,9 +232,11 @@ static int _compat_vdpa_reset(struct vhost_vdpa *v) > struct vdpa_device *vdpa = v->vdpa; > u32 flags = 0; > > - flags |= !vhost_backend_has_feature(v->vdev.vqs[0], > - VHOST_BACKEND_F_IOTLB_PERSIST) ? > - VDPA_RESET_F_CLEAN_MAP : 0; > + if (v->vdev.vqs) { > + flags |= !vhost_backend_has_feature(v->vdev.vqs[0], > + > VHOST_BACKEND_F_IOTLB_PERSIST) ? > + VDPA_RESET_F_CLEAN_MAP : 0; > + } > > return vdpa_reset(vdpa, flags); > } _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization