From: Kevin Wolf <kwolf@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org,
Fam Zheng <famz@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] file-posix: clean up max_segments buffer termination
Date: Tue, 14 Mar 2017 10:25:49 +0100 [thread overview]
Message-ID: <20170314092549.GA3952@noname.str.redhat.com> (raw)
In-Reply-To: <20170314090922.28083-1-stefanha@redhat.com>
Am 14.03.2017 um 10:09 hat Stefan Hajnoczi geschrieben:
> The following pattern is unsafe:
>
> char buf[32];
> ret = read(fd, buf, sizeof(buf));
> ...
> buf[ret] = 0;
>
> If read(2) returns 32 then a byte beyond the end of the buffer is
> zeroed.
>
> In practice this buffer overflow does not occur because the sysfs
> max_segments file only contains an unsigned short + '\n'. The string is
> always shorter than 32 bytes.
>
> Regardless, avoid this pattern because static analysis tools might
> complain and it could lead to real buffer overflows if copy-pasted
> elsewhere in the codebase.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Oops. I should have found this during review. Thanks for catching it.
Thanks, applied to the block branch.
Kevin
next prev parent reply other threads:[~2017-03-14 9:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-14 9:09 [Qemu-devel] [PATCH] file-posix: clean up max_segments buffer termination Stefan Hajnoczi
2017-03-14 9:25 ` Kevin Wolf [this message]
2017-03-14 9:42 ` Fam Zheng
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