[PATCH 3.16 199/366] RDMA/uverbs: Fix slab-out-of-bounds in ib_uverbs_ex_create_flow

Ben Hutchings
2018-11-12T06:06:24Z

From: Leon Romanovsky <leonro@mellanox.com>

commit 4fae7f170416f970e5655f7e945ce69286b1c4ff upstream.

The check of cmd.flow_attr.size should check into account the size of the
reserved field (2 bytes), otherwise user can provide a size which will
cause a slab-out-of-bounds warning below.

==================================================================
BUG: KASAN: slab-out-of-bounds in ib_uverbs_ex_create_flow+0x1740/0x1d00
Read of size 2 at addr ffff880068dff1a6 by task syz-executor775/269

CPU: 0 PID: 269 Comm: syz-executor775 Not tainted 4.18.0-rc1+ #245
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.11.0-0-g63451fca13-prebuilt.qemu-project.org 04/01/2014
Call Trace:
dump_stack+0xef/0x17e
print_address_description+0x83/0x3b0
kasan_report+0x18d/0x4d0
ib_uverbs_ex_create_flow+0x1740/0x1d00
ib_uverbs_write+0x923/0x1010
__vfs_write+0x10d/0x720
vfs_write+0x1b0/0x550
ksys_write+0xc6/0x1a0
do_syscall_64+0xa7/0x590
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x433899
Code: fd ff 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 48 89 f8 48 89
f7 48 89 d6 48 89 ca 4d 89 c2 4d
89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 3b 91 fd ff c3 66
2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc2724db58 EFLAGS: 00000217 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000020006880 RCX: 0000000000433899
RDX: 00000000000000e0 RSI: 0000000020002480 RDI: 0000000000000003
RBP: 00000000006d7018 R08: 00000000004002f8 R09: 00000000004002f8
R10: 00000000004002f8 R11: 0000000000000217 R12: 0000000000000000

R13: 000000000040cd20 R14: 000000000040cdb0 R15: 0000000000000006

Allocated by task 269:
kasan_kmalloc+0xa0/0xd0
__kmalloc+0x1a9/0x510
ib_uverbs_ex_create_flow+0x26c/0x1d00
ib_uverbs_write+0x923/0x1010
__vfs_write+0x10d/0x720
vfs_write+0x1b0/0x550
ksys_write+0xc6/0x1a0
do_syscall_64+0xa7/0x590
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
__kasan_slab_free+0x12e/0x180
kfree+0x159/0x630
detach_buf+0x559/0x7a0
virtqueue_get_buf_ctx+0x3cc/0xab0
virtblk_done+0x1eb/0x3d0
vring_interrupt+0x16d/0x2b0
__handle_irq_event_percpu+0x10a/0x980
handle_irq_event_percpu+0x77/0x190
handle_irq_event+0xc6/0x1a0
handle_edge_irq+0x211/0xd80
handle_irq+0x3d/0x60
do_IRQ+0x9b/0x220

The buggy address belongs to the object at ffff880068dff180
which belongs to the cache kmalloc-64 of size 64
The buggy address is located 38 bytes inside of
64-byte region [ffff880068dff180, ffff880068dff1c0)
The buggy address belongs to the page:
page:ffffea0001a37fc0 count:1 mapcount:0 mapping:ffff88006c401780
index:0x0
flags: 0x4000000000000100(slab)
raw: 4000000000000100 ffffea0001a31100 0000001100000011 ffff88006c401780
raw: 0000000000000000 00000000802a002a 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff880068dff080: fb fb fb fb fc fc fc fc fb fb fb fb fb fb fb fb
ffff880068dff100: fc fc fc fc fb fb fb fb fb fb fb fb fc fc fc fc
>ffff880068dff180: 00 00 00 00 07 fc fc fc fc fc fc fc fb fb fb fb
^
ffff880068dff200: fb fb fb fb fc fc fc fc 00 00 00 00 00 00 fc fc
ffff880068dff280: fc fc fc fc 00 00 00 00 00 00 00 00 fc fc fc fc
==================================================================

Fixes: f88482743872 ("IB/core: clarify overflow/underflow checks on ib_create/destroy_flow")
Cc: syzkaller <syzkaller@googlegroups.com>
Reported-by: Noa Osherovich <noaos@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/infiniband/core/uverbs_cmd.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)

--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -2674,8 +2674,8 @@ int ib_uverbs_ex_create_flow(struct ib_u
struct ib_uverbs_flow_attr *kern_flow_attr;
struct ib_flow_attr *flow_attr;
struct ib_qp *qp;
+ struct ib_uverbs_flow_spec_hdr *kern_spec;
int err = 0;
- void *kern_spec;
void *ib_spec;
int i;

@@ -2717,8 +2717,8 @@ int ib_uverbs_ex_create_flow(struct ib_u
if (!kern_flow_attr)
return -ENOMEM;

- memcpy(kern_flow_attr, &cmd.flow_attr, sizeof(*kern_flow_attr));
- err = ib_copy_from_udata(kern_flow_attr + 1, ucore,
+ *kern_flow_attr = cmd.flow_attr;
+ err = ib_copy_from_udata(&kern_flow_attr->flow_specs, ucore,
cmd.flow_attr.size);
if (err)
goto err_free_attr;
@@ -2758,19 +2758,21 @@ int ib_uverbs_ex_create_flow(struct ib_u
flow_attr->flags = kern_flow_attr->flags;
flow_attr->size = sizeof(*flow_attr);

- kern_spec = kern_flow_attr + 1;
+ kern_spec = kern_flow_attr->flow_specs;
ib_spec = flow_attr + 1;
for (i = 0; i < flow_attr->num_of_specs &&
- cmd.flow_attr.size > offsetof(struct ib_uverbs_flow_spec, reserved) &&
- cmd.flow_attr.size >=
- ((struct ib_uverbs_flow_spec *)kern_spec)->size; i++) {
- err = kern_spec_to_ib_spec(kern_spec, ib_spec);
+ cmd.flow_attr.size > sizeof(*kern_spec) &&
+ cmd.flow_attr.size >= kern_spec->size;
+ i++) {
+ err = kern_spec_to_ib_spec(
+ (struct ib_uverbs_flow_spec *)kern_spec,
+ ib_spec);
if (err)
goto err_free;
flow_attr->size +=
((union ib_flow_spec *) ib_spec)->size;
- cmd.flow_attr.size -= ((struct ib_uverbs_flow_spec *)kern_spec)->size;
- kern_spec += ((struct ib_uverbs_flow_spec *) kern_spec)->size;
+ cmd.flow_attr.size -= kern_spec->size;
+ kern_spec = ((void *)kern_spec) + kern_spec->size;
ib_spec += ((union ib_flow_spec *) ib_spec)->size;
}
if (cmd.flow_attr.size || (i != flow_attr->num_of_specs)) {