[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing |
Date: |
Fri, 17 Feb 2012 13:35:02 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux) |
"Michael S. Tsirkin" <address@hidden> writes:
> On Thu, Feb 16, 2012 at 01:39:02PM -0700, Eric Blake wrote:
>> On 02/16/2012 12:23 PM, malc wrote:
>> > On Thu, 16 Feb 2012, Michael S. Tsirkin wrote:
>> >
>> >> Use scanf instead of manual string scanning.
>> >>
>> >> +
>> >> + /* Parse [[<domain>:]<bus>:]<slot> */
>> >> + sscanf(addr, "%x:%x:%x%n", &dom, &bus, &slot, &n);
>> >
>> > sscanf can fail.
>>
>> Worse, the *scanf family has undefined behavior on integer overflow. If
>> addr contains "100000000000000:0:0", there's no telling whether it will
>> be diagnosed as a parse error, or silently accepted and truncated, in
>> which case, there's no telling what dom will contain.
>>
>> I cringe any time I see someone using scanf to parse numbers from
>> arbitrary user input; I barely tolerate it for parsing things generated
>> by the kernel, but even there, I won't ever use scanf myself.
>> Same goes
>> for atoi. _Only_ strtol and friends can robustly parse arbitrary input
>> into integers.
>
> Seems easy to fix: I'll just set maximum field width of 8.
Nope. Functional change: "000000001.2" is no longer accepted.
> Any other issues?
Yes.
1. More functional changes, e.g.
* "1" is no longer rejected when funcp != NULL
Probably more. I'd be particularly wary of sscanf()'s appetite for
space.
2. Diffstat: 1 files changed, 38 insertions(+), 43 deletions(-)
Why bother?
- [Qemu-devel] [PATCH 0/2] pci devaddr parsing cleanups, Michael S. Tsirkin, 2012/02/16
- [Qemu-devel] [PATCH 1/2] pci: don't export an internal function, Michael S. Tsirkin, 2012/02/16
- [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing, Michael S. Tsirkin, 2012/02/16
- Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing, malc, 2012/02/16
- Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing, Eric Blake, 2012/02/16
- Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing, malc, 2012/02/16
- Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing, Michael S. Tsirkin, 2012/02/17
- Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing,
Markus Armbruster <=
- Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing, Michael S. Tsirkin, 2012/02/19
- Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing, Michael S. Tsirkin, 2012/02/19
- Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing, Michael S. Tsirkin, 2012/02/17
- Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing, malc, 2012/02/17
- Re: [Qemu-devel] [PATCH 2/2] pci: rewrite devaddr parsing, Michael S. Tsirkin, 2012/02/17