From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>, Ingo Molnar <mingo@elte.hu>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
David Long <dave.long@linaro.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] uprobes: Fix the memory out of bound overwrite in copy_insn()
Date: Wed, 13 Nov 2013 16:08:37 +0530 [thread overview]
Message-ID: <20131113103837.GB543@linux.vnet.ibm.com> (raw)
In-Reply-To: <20131107194032.GB29154@redhat.com>
* Oleg Nesterov <oleg@redhat.com> [2013-11-07 20:40:32]:
> 1. copy_insn() doesn't look very nice, all calculations are
> confusing and it is not immediately clear why do we read
> the 2nd page first.
>
> 2. The usage of inode->i_size is wrong on 32-bit machines.
>
> 3. "Instruction at end of binary" logic is simply wrong, it
> doesn't handle the case when uprobe->offset > inode->i_size.
>
> In this case "bytes" overflows, and __copy_insn() writes to
> the memory outside of uprobe->arch.insn.
>
> Yes, uprobe_register() checks i_size_read(), but this file
> can be truncated after that. All i_size checks are racy, we
> do this only to catch the obvious mistakes.
>
> Change copy_insn() to call __copy_insn() in a loop, simplify
> and fix the bytes/nbytes calculations.
>
> Note: we do not care if offset + size > i_size, the users of
> arch_uprobe->insn can't know how many bytes were actually copied
> anyway. But perhaps this needs more changes.
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
--
Thanks and Regards
Srikar Dronamraju
prev parent reply other threads:[~2013-11-13 10:49 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-06 19:19 [GIT PULL] uprobes: preparations for arm port Oleg Nesterov
2013-11-07 5:36 ` Srikar Dronamraju
2013-11-07 7:48 ` Ingo Molnar
2013-11-07 7:51 ` Ingo Molnar
2013-11-07 14:34 ` Oleg Nesterov
2013-11-07 15:16 ` Ingo Molnar
2013-11-07 16:27 ` Oleg Nesterov
2013-11-07 19:40 ` [PATCH 0/1] uprobes: Fix the memory out of bound overwrite in copy_insn() Oleg Nesterov
2013-11-07 19:40 ` [PATCH 1/1] " Oleg Nesterov
2013-11-08 16:24 ` Oleg Nesterov
2013-11-13 10:38 ` Srikar Dronamraju [this message]
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