Date:   Mon, 10 May 2021 16:22:29 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     Doug Ledford <dledford@...hat.com>,
        Leon Romanovsky <leonro@...dia.com>,
        Avihai Horon <avihaih@...dia.com>,
        linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org
Subject: Re: [PATCH rdma-rc] RDMA/core: Prevent divide-by-zero error
 triggered by the user

On Mon, May 10, 2021 at 05:46:00PM +0300, Leon Romanovsky wrote:
> From: Leon Romanovsky <leonro@...dia.com>
> 
> The user_entry_size is supplied by the user and later used as a
> denominator to calculate number of entries. The zero supplied by
> the user will trigger the following divide-by-zero error:
> 
>  divide error: 0000 [#1] SMP KASAN PTI
>  CPU: 4 PID: 497 Comm: c_repro Not tainted 5.13.0-rc1+ #281
>  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
>  RIP: 0010:ib_uverbs_handler_UVERBS_METHOD_QUERY_GID_TABLE+0x1b1/0x510
>  Code: 87 59 03 00 00 e8 9f ab 1e ff 48 8d bd a8 00 00 00 e8 d3 70 41 ff 44 0f b7 b5 a8 00 00 00 e8 86 ab 1e ff 31 d2 4c 89 f0 31 ff <49> f7 f5 48 89 d6 48 89 54 24 10 48 89 04 24 e8 1b ad 1e ff 48 8b
>  RSP: 0018:ffff88810416f828 EFLAGS: 00010246
>  RAX: 0000000000000008 RBX: 1ffff1102082df09 RCX: ffffffff82183f3d
>  RDX: 0000000000000000 RSI: ffff888105f2da00 RDI: 0000000000000000
>  RBP: ffff88810416fa98 R08: 0000000000000001 R09: ffffed102082df5f
>  R10: ffff88810416faf7 R11: ffffed102082df5e R12: 0000000000000000
>  R13: 0000000000000000 R14: 0000000000000008 R15: ffff88810416faf0
>  FS:  00007f5715efa740(0000) GS:ffff88811a700000(0000) knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: 0000000020000840 CR3: 000000010c2e0001 CR4: 0000000000370ea0
>  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>  Call Trace:
>   ? ib_uverbs_handler_UVERBS_METHOD_INFO_HANDLES+0x4b0/0x4b0
>   ? __radix_tree_lookup+0x190/0x190
>   ? write_comp_data+0x2a/0x80
>   ? __sanitizer_cov_trace_pc+0x1d/0x50
>   ? __bitmap_subset+0x9a/0x130
>   ib_uverbs_cmd_verbs+0x1546/0x1940
>   ? __kernel_text_address+0xe/0x30
>   ? ib_uverbs_handler_UVERBS_METHOD_INFO_HANDLES+0x4b0/0x4b0
>   ? uverbs_fill_udata+0x510/0x510
>   ? putname+0xa8/0xc0
>   ? kasan_set_free_info+0x20/0x30
>   ? __kasan_slab_free+0xed/0x130
>   ? kmem_cache_free+0x94/0x410
>   ? putname+0xa8/0xc0
>   ? do_sys_openat2+0x477/0x780
>   ? do_sys_open+0xc8/0x150
>   ? __sanitizer_cov_trace_pc+0x1d/0x50
>   ? restore_nameidata+0x8a/0xb0
>   ? __sanitizer_cov_trace_pc+0x1d/0x50
>   ? do_filp_open+0x166/0x1f0
>   ? should_fail+0x78/0x2a0
>   ? may_open_dev+0x80/0x80
>   ? write_comp_data+0x2a/0x80
>   ? __sanitizer_cov_trace_pc+0x1d/0x50
>   ib_uverbs_ioctl+0x186/0x240
>   ? ib_uverbs_cmd_verbs+0x1940/0x1940
>   ? fsnotify+0xba0/0xba0
>   ? write_comp_data+0x2a/0x80
>   ? write_comp_data+0x2a/0x80
>   ? ib_uverbs_cmd_verbs+0x1940/0x1940
>   __x64_sys_ioctl+0x38a/0x1220
>   ? generic_block_fiemap+0x60/0x60
>   ? putname+0xa8/0xc0
>   ? __sanitizer_cov_trace_pc+0x1d/0x50
>   ? do_sys_openat2+0x47c/0x780
>   ? file_open_root+0x420/0x420
>   ? __sanitizer_cov_trace_pc+0x1d/0x50
>   ? cgroup_rstat_updated+0x66/0x1a0
>   ? do_sys_open+0xc8/0x150
>   ? filp_open+0x80/0x80
>   ? write_comp_data+0x2a/0x80
>   ? fpregs_assert_state_consistent+0x90/0xa0
>   ? __sanitizer_cov_trace_pc+0x1d/0x50
>   ? exit_to_user_mode_prepare+0x35/0x160
>   do_syscall_64+0x3f/0x80
>   entry_SYSCALL_64_after_hwframe+0x44/0xae
>  RIP: 0033:0x7f5715ff0f59
>  Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 73 01 c3 48 8b 0d 07 6f 0c 00 f7 d8 64 89 01 48
>  RSP: 002b:00007ffd33031858 EFLAGS: 00000213 ORIG_RAX: 0000000000000010
>  RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5715ff0f59
>  RDX: 0000000020000180 RSI: 00000000c0181b01 RDI: 0000000000000003
>  RBP: 00007ffd33031870 R08: 00007ffd33031950 R09: 00007ffd33031950
>  R10: 0000000000000000 R11: 0000000000000213 R12: 0000558a0989b060
>  R13: 00007ffd33031950 R14: 0000000000000000 R15: 0000000000000000
>  Modules linked in:
>  Dumping ftrace buffer:
>     (ftrace buffer empty)
>  ---[ end trace 7776f38b0b269133 ]---
>  RIP: 0010:ib_uverbs_handler_UVERBS_METHOD_QUERY_GID_TABLE+0x1b1/0x510
>  Code: 87 59 03 00 00 e8 9f ab 1e ff 48 8d bd a8 00 00 00 e8 d3 70 41 ff 44 0f b7 b5 a8 00 00 00 e8 86 ab 1e ff 31 d2 4c 89 f0 31 ff <49> f7 f5 48 89 d6 48 89 54 24 10 48 89 04 24 e8 1b ad 1e ff 48 8b
>  RSP: 0018:ffff88810416f828 EFLAGS: 00010246
>  RAX: 0000000000000008 RBX: 1ffff1102082df09 RCX: ffffffff82183f3d
>  RDX: 0000000000000000 RSI: ffff888105f2da00 RDI: 0000000000000000
>  RBP: ffff88810416fa98 R08: 0000000000000001 R09: ffffed102082df5f
>  R10: ffff88810416faf7 R11: ffffed102082df5e R12: 0000000000000000
>  R13: 0000000000000000 R14: 0000000000000008 R15: ffff88810416faf0
>  FS:  00007f5715efa740(0000) GS:ffff88811a700000(0000) knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: 0000000020000840 CR3: 000000010c2e0001 CR4: 0000000000370ea0
>  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>  Kernel panic - not syncing: Fatal exception
>  Dumping ftrace buffer:
>     (ftrace buffer empty)
>  Kernel Offset: disabled
>  Rebooting in 1 seconds..
> 
> Fixes: 9f85cbe50aa0 ("RDMA/uverbs: Expose the new GID query API to user space")
> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
> Signed-off-by: Leon Romanovsky <leonro@...dia.com>
> ---
>  drivers/infiniband/core/uverbs_std_types_device.c | 3 +++
>  1 file changed, 3 insertions(+)

Applied to for-rc, thanks

Jason

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