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Re: [Qemu-devel] [PATCH v2] migration: fix crash in when incoming client
From: |
Juan Quintela |
Subject: |
Re: [Qemu-devel] [PATCH v2] migration: fix crash in when incoming client channel setup fails |
Date: |
Tue, 19 Jun 2018 22:04:25 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
Daniel P. Berrangé <address@hidden> wrote:
> The way we determine if we can start the incoming migration was
> changed to use migration_has_all_channels() in:
>
> commit 428d89084c709e568f9cd301c2f6416a54c53d6d
> Author: Juan Quintela <address@hidden>
> Date: Mon Jul 24 13:06:25 2017 +0200
>
> migration: Create migration_has_all_channels
>
> This method in turn calls multifd_recv_all_channels_created()
> which is hardcoded to always return 'true' when multifd is
> not in use. This is a latent bug...
>
> ...activated in in a following commit where that return result
> ends up acting as the flag to indicate whether it is possible
> to start processing the migration:
>
> commit 36c2f8be2c4eb0003ac77a14910842b7ddd7337e
> Author: Juan Quintela <address@hidden>
> Date: Wed Mar 7 08:40:52 2018 +0100
>
> migration: Delay start of migration main routines
>
> This means that if channel initialization fails with normal
> migration, it'll never notice and attempt to start the
> incoming migration regardless and crash on a NULL pointer.
>
> This can be seen, for example, if a client connects to a server
> requiring TLS, but has an invalid x509 certificate:
>
> qemu-system-x86_64: The certificate hasn't got a known issuer
> qemu-system-x86_64: migration/migration.c:386: process_incoming_migration_co:
> Assertion `mis->from_src_file' failed.
>
> #0 0x00007fffebd24f2b in raise () at /lib64/libc.so.6
> #1 0x00007fffebd0f561 in abort () at /lib64/libc.so.6
> #2 0x00007fffebd0f431 in _nl_load_domain.cold.0 () at /lib64/libc.so.6
> #3 0x00007fffebd1d692 in () at /lib64/libc.so.6
> #4 0x0000555555ad027e in process_incoming_migration_co (opaque=<optimized
> out>) at migration/migration.c:386
> #5 0x0000555555c45e8b in coroutine_trampoline (i0=<optimized out>,
> i1=<optimized out>) at util/coroutine-ucontext.c:116
> #6 0x00007fffebd3a6a0 in __start_context () at /lib64/libc.so.6
> #7 0x0000000000000000 in ()
>
> To handle the non-multifd case, we check whether mis->from_src_file
> is non-NULL. With this in place, the migration server drops the
> rejected client and stays around waiting for another, hopefully
> valid, client to arrive.
>
> Signed-off-by: Daniel P. Berrangé <address@hidden>
Reviewed-by: Juan Quintela <address@hidden>