[PATCH 4.20 61/80] IB/uverbs: Fix OOPs in uverbs_user_mmap_disassociate

Greg Kroah-Hartman
2019-02-04T10:53:12Z

From: Yishai Hadas <yishaih@mellanox.com>

commit 7b21b69ab203136fdc153c7707fa6c409e523c2e upstream.

The vma->vm_mm can become impossible to get before rdma_umap_close() is
called, in this case we must not try to get an mm that is already
undergoing process exit. In this case there is no need to wait for
anything as the VMA will be destroyed by another thread soon and is
already effectively 'unreachable' by userspace.

BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
PGD 800000012bc50067 P4D 800000012bc50067 PUD 129db5067 PMD 0
Oops: 0000 [#1] SMP PTI
CPU: 1 PID: 2050 Comm: bash Tainted: G W OE 4.20.0-rc6+ #3
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
RIP: 0010:__rb_erase_color+0xb9/0x280
Code: 84 17 01 00 00 48 3b 68 10 0f 84 15 01 00 00 48 89
58 08 48 89 de 48 89 ef 4c 89 e3 e8 90 84 22 00 e9 60 ff ff ff 48 8b 5d
10 <f6> 03 01 0f 84 9c 00 00 00 48 8b 43 10 48 85 c0 74 09 f6 00 01 0f
RSP: 0018:ffffbecfc090bab8 EFLAGS: 00010246
RAX: ffff97616346cf30 RBX: 0000000000000000 RCX: 0000000000000101
RDX: 0000000000000000 RSI: ffff97623b6ca828 RDI: ffff97621ef10828
RBP: ffff97621ef10828 R08: ffff97621ef10828 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff97623b6ca838
R13: ffffffffbb3fef50 R14: ffff97623b6ca828 R15: 0000000000000000
FS: 00007f7a5c31d740(0000) GS:ffff97623bb00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000011255a000 CR4: 00000000000006e0
Call Trace:
unlink_file_vma+0x3b/0x50
free_pgtables+0xa1/0x110
exit_mmap+0xca/0x1a0
? mlx5_ib_dealloc_pd+0x28/0x30 [mlx5_ib]
mmput+0x54/0x140
uverbs_user_mmap_disassociate+0xcc/0x160 [ib_uverbs]
uverbs_destroy_ufile_hw+0xf7/0x120 [ib_uverbs]
ib_uverbs_remove_one+0xea/0x240 [ib_uverbs]
ib_unregister_device+0xfb/0x200 [ib_core]
mlx5_ib_remove+0x51/0xe0 [mlx5_ib]
mlx5_remove_device+0xc1/0xd0 [mlx5_core]
mlx5_unregister_device+0x3d/0xb0 [mlx5_core]
remove_one+0x2a/0x90 [mlx5_core]
pci_device_remove+0x3b/0xc0
device_release_driver_internal+0x16d/0x240
unbind_store+0xb2/0x100
kernfs_fop_write+0x102/0x180
__vfs_write+0x36/0x1a0
? __alloc_fd+0xa9/0x170
? set_close_on_exec+0x49/0x70
vfs_write+0xad/0x1a0
ksys_write+0x52/0xc0
do_syscall_64+0x5b/0x180
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Cc: <stable@vger.kernel.org> # 4.19
Fixes: 5f9794dc94f5 ("RDMA/ucontext: Add a core API for mmaping driver IO memory")
Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/infiniband/core/uverbs_main.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)

--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -1000,11 +1000,19 @@ void uverbs_user_mmap_disassociate(struc

/* Get an arbitrary mm pointer that hasn't been cleaned yet */
mutex_lock(&ufile->umap_lock);
- if (!list_empty(&ufile->umaps)) {
- mm = list_first_entry(&ufile->umaps,
- struct rdma_umap_priv, list)
- ->vma->vm_mm;
- mmget(mm);
+ while (!list_empty(&ufile->umaps)) {
+ int ret;
+
+ priv = list_first_entry(&ufile->umaps,
+ struct rdma_umap_priv, list);
+ mm = priv->vma->vm_mm;
+ ret = mmget_not_zero(mm);
+ if (!ret) {
+ list_del_init(&priv->list);
+ mm = NULL;
+ continue;
+ }
+ break;
}
mutex_unlock(&ufile->umap_lock);
if (!mm)