[dpdk-dev] [PATCH] net/failsafe: fix parameters parsing
Gaëtan Rivet
gaetan.rivet at 6wind.com
Thu Aug 17 17:25:46 CEST 2017
Hi Matan,
Thanks for spotting the bug.
On Thu, Aug 17, 2017 at 05:19:41PM +0300, Matan Azrad wrote:
> The corrupted code used wrongly snprintf return value as the
> number of characters actually copied, in spite of the meanning
> is the number of characters which would be generated for the
> given input.
>
> It caused to remain zerod bytes between the failsafe command line
> non sub device parameters indicates end of string.
>
> Hence, when rte_kvargs_parse tried to parse all parameters, it
> got end of string after the first one and the others weren't parsed.
>
> So, if the mac parameters was the first in command line it was
> taken while hotplug_poll was left default, and vice versa.
>
> The fix updates the buffer index by dedicated variable contains
> the copy size, by the way uses memcpy instead of snprintf
> which is good enouth for this copy scenario.
Actually snprintf should still be used.
>
> Fixes: a46f8d584eb8 ("net/failsafe: add fail-safe PMD")
> Cc: stable at dpdk.org
>
> Signed-off-by: Matan Azrad <matan at mellanox.com>
> ---
> drivers/net/failsafe/failsafe_args.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/failsafe/failsafe_args.c b/drivers/net/failsafe/failsafe_args.c
> index 1f22416..0a98b04 100644
> --- a/drivers/net/failsafe/failsafe_args.c
> +++ b/drivers/net/failsafe/failsafe_args.c
> @@ -271,7 +271,7 @@ static int
> fs_remove_sub_devices_definition(char params[DEVARGS_MAXLEN])
> {
> char buffer[DEVARGS_MAXLEN] = {0};
> - size_t a, b;
> + size_t a, b, temp;
temp is not descriptive enough.
You are declaring this variable here because you want to re-use it
instead of `start`. This is an overreach however, this fix must be
restricted to the actual bug.
> int i;
>
> a = 0;
> @@ -286,12 +286,14 @@ fs_remove_sub_devices_definition(char params[DEVARGS_MAXLEN])
> ERROR("Invalid parameter");
> return -EINVAL;
> }
> - if (params[b] == ',' || params[b] == '\0')
Declare the temporary variable in this scope, with a descriptive name
such as "len", "length", "param_len" or something close.
> - i += snprintf(&buffer[i], b - a + 1, "%s", ¶ms[a]);
> - if (params[b] == '(') {
> - size_t start = b;
> + if (params[b] == ',' || params[b] == '\0') {
> + temp = b - a + 1;
The value here should be "b - a".
If a != 0 however, then we are parsing a new parameter and buffer
already contains at least one. A comma should be added to separate the
two.
An example might clarify what I mean:
if (params[b] == ',' || params[b] == '\0') {
size_t param_len = b - a;
if (a)
param_len += 1;
snprintf(&buffer[i], param_len + 1, "%s%s",
a ? "," : "", ¶ms[a]);
i += param_len;
}
The conditionals about `a` are ugly however, if you find a better way to write
those you are most welcome :).
> + memcpy(&buffer[i], ¶ms[a], temp);
> + i += temp;
> + } else if (params[b] == '(') {
> + temp = b;
> b += closing_paren(¶ms[b]);
> - if (b == start)
The changes should be limited to the actual bug. No need to change this.
> + if (b == temp)
> return -EINVAL;
> b += 1;
> if (params[b] == '\0')
> --
> 2.7.4
>
Thanks again for the debug and sorry for being nitpicky.
--
Gaëtan Rivet
6WIND
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