Re: [PATCH rdma-next] RDMA/core: Fix protection fault in get_pkey_idx_qp_list

[Leon Romanovsky <leonro@mellanox.com>]

On Sun, Jan 26, 2020 at 07:15:53PM +0200, Leon Romanovsky wrote:
> From: Maor Gottlieb <maorg@mellanox.com>
>
> We don't need to set pkey as valid in case that user set only one
> of pkey index or port number, otherwise it will be resulted in NULL
> pointer dereference while accessing to uninitialized pkey list.
>
> The following crash from syzkaller revealed it.
>
> kasan: CONFIG_KASAN_INLINE enabled
> kasan: GPF could be caused by NULL-ptr deref or user memory access
> general protection fault: 0000 [#1] SMP KASAN PTI
> CPU: 1 PID: 14753 Comm: syz-executor.2 Not tainted 5.5.0-rc5 #2
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
> RIP: 0010:get_pkey_idx_qp_list+0x161/0x2d0
> Code: 01 00 00 49 8b 5e 20 4c 39 e3 0f 84 b9 00 00 00 e8 e4 42 6e fe 48
> 8d 7b 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04
> 02 84 c0 74 08 3c 01 0f 8e d0 00 00 00 48 8d 7d 04 48 b8
> RSP: 0018:ffffc9000bc6f950 EFLAGS: 00010202
> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff82c8bdec
> RDX: 0000000000000002 RSI: ffffc900030a8000 RDI: 0000000000000010
> RBP: ffff888112c8ce80 R08: 0000000000000004 R09: fffff5200178df1f
> R10: 0000000000000001 R11: fffff5200178df1f R12: ffff888115dc4430
> R13: ffff888115da8498 R14: ffff888115dc4410 R15: ffff888115da8000
> FS:  00007f20777de700(0000) GS:ffff88811b100000(0000)
> knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000001b2f721000 CR3: 00000001173ca002 CR4: 0000000000360ee0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  port_pkey_list_insert+0xd7/0x7c0
>  ib_security_modify_qp+0x6fa/0xfc0
>  _ib_modify_qp+0x8c4/0xbf0
>  modify_qp+0x10da/0x16d0
>  ib_uverbs_modify_qp+0x9a/0x100
>  ib_uverbs_write+0xaa5/0xdf0
>  __vfs_write+0x7c/0x100
>  vfs_write+0x168/0x4a0
>  ksys_write+0xc8/0x200
>  do_syscall_64+0x9c/0x390
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Fixes: d291f1a652329 ("IB/core: Enforce PKey security on QPs")
> Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
> Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
> ---
>  drivers/infiniband/core/security.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>

As Maor explained below, the code is correct, so what is the resolution here?

Thanks