The rdma_ah_find_type() accesses the port array based on an index
controlled by userspace. The existing bounds check is after the first use
of the index, so userspace can generate an out of bounds access, as shown
by the KASN report below.
==================================================================
BUG: KASAN: slab-out-of-bounds in to_rdma_ah_attr+0xa8/0x3b0
Read of size 4 at addr ffff880019ae2268 by task ibv_rc_pingpong/409
CPU: 0 PID: 409 Comm: ibv_rc_pingpong Not tainted 4.15.0-rc2-00031-gb60a3faf5b83-dirty #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
Call Trace:
dump_stack+0xe9/0x18f
print_address_description+0xa2/0x350
kasan_report+0x3a5/0x400
to_rdma_ah_attr+0xa8/0x3b0
mlx5_ib_query_qp+0xd35/0x1330
ib_query_qp+0x8a/0xb0
ib_uverbs_query_qp+0x237/0x7f0
ib_uverbs_write+0x617/0xd80
__vfs_write+0xf7/0x500
vfs_write+0x149/0x310
SyS_write+0xca/0x190
entry_SYSCALL_64_fastpath+0x18/0x85
RIP: 0033:0x7fe9c7a275a0
RSP: 002b:00007ffee5498738 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fe9c7ce4b00 RCX: 00007fe9c7a275a0
RDX: 0000000000000018 RSI: 00007ffee5498800 RDI: 0000000000000003
RBP: 000055d0c8d3f010 R08: 00007ffee5498800 R09: 0000000000000018
R10: 00000000000000ba R11: 0000000000000246 R12: 0000000000008000
R13: 0000000000004fb0 R14: 000055d0c8d3f050 R15: 00007ffee5498560
Allocated by task 1:
__kmalloc+0x3f9/0x430
alloc_mad_private+0x25/0x50
ib_mad_post_receive_mads+0x204/0xa60
ib_mad_init_device+0xa59/0x1020
ib_register_device+0x83a/0xbc0
mlx5_ib_add+0x50e/0x5c0
mlx5_add_device+0x142/0x410
mlx5_register_interface+0x18f/0x210
mlx5_ib_init+0x56/0x63
do_one_initcall+0x15b/0x270
kernel_init_freeable+0x2d8/0x3d0
kernel_init+0x14/0x190
ret_from_fork+0x24/0x30
Freed by task 0:
(stack is not available)
The buggy address belongs to the object at ffff880019ae2000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 104 bytes to the right of
512-byte region [ffff880019ae2000, ffff880019ae2200)
The buggy address belongs to the page:
page:000000005d674e18 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0
flags: 0x4000000000008100(slab|head)
raw: 4000000000008100 0000000000000000 0000000000000000 00000001000c000c
raw: dead000000000100 dead000000000200 ffff88001a402000 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff880019ae2100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff880019ae2180: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
>ffff880019ae2200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff880019ae2280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff880019ae2300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
Disabling lock debugging due to kernel taint
Cc: <stable@vger.kernel.org>
Fixes: 44c58487d5 ("IB/core: Define 'ib' and 'roce' rdma_ah_attr types")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
ae59c3f0b6