From: Christian Schoenebeck <qemu_oss@crudebyte.com>
To: qemu-devel@nongnu.org
Cc: Vitaly Chikunov <vt@altlinux.org>, Greg Kurz <groug@kaod.org>,
qemu-stable@nongnu.org, "Dmitry V . Levin" <ldv@altlinux.org>
Subject: Re: [PATCH v5] 9pfs: Fix segfault in do_readdir_many caused by struct dirent overread
Date: Thu, 17 Feb 2022 17:30:11 +0100 [thread overview]
Message-ID: <2135244.TdAzAAGDzu@silver> (raw)
In-Reply-To: <20220216181821.3481527-1-vt@altlinux.org>
On Mittwoch, 16. Februar 2022 19:18:21 CET Vitaly Chikunov wrote:
> `struct dirent' returned from readdir(3) could be shorter (or longer)
> than `sizeof(struct dirent)', thus memcpy of sizeof length will overread
> into unallocated page causing SIGSEGV. Example stack trace:
>
> #0 0x00005555559ebeed v9fs_co_readdir_many (/usr/bin/qemu-system-x86_64 +
> 0x497eed) #1 0x00005555559ec2e9 v9fs_readdir (/usr/bin/qemu-system-x86_64
> + 0x4982e9) #2 0x0000555555eb7983 coroutine_trampoline
> (/usr/bin/qemu-system-x86_64 + 0x963983) #3 0x00007ffff73e0be0 n/a (n/a +
> 0x0)
>
> While fixing this, provide a helper for any future `struct dirent' cloning.
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/841
> Cc: qemu-stable@nongnu.org
> Co-authored-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
> Reviewed-by: Dmitry V. Levin <ldv@altlinux.org>
> Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
> ---
Queued on 9p.next:
https://github.com/cschoenebeck/qemu/commits/9p.next
Thanks! I prepare a new PR now.
Best regards,
Christian Schoenebeck
prev parent reply other threads:[~2022-02-17 16:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-16 18:18 [PATCH v5] 9pfs: Fix segfault in do_readdir_many caused by struct dirent overread Vitaly Chikunov
2022-02-17 9:26 ` Christian Schoenebeck
2022-02-17 13:06 ` Vitaly Chikunov
2022-02-17 12:35 ` Greg Kurz
2022-02-17 16:30 ` Christian Schoenebeck [this message]
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