Re: [PATCH] net/failsafe: fix exec parameter parsing error flow
From: Gaëtan Rivet <hidden>
Date: 2017-08-29 16:33:49
Hi Matan, On Tue, Aug 29, 2017 at 05:59:08PM +0300, Matan Azrad wrote:
The corrupted code returns success value in case of the execution process output stream is empty(EOF). It causes to segmentation fault while failsafe polls this command line again, than gets success and tries to do hotplug add to the sub device by uninitialized pointer dereferencing.
This is a bug and should be fixed, thanks.
Morever, when the output is not empty but uncorrect, failsafe returns error for its probe function while the expected behavior is to do polling until the output is correct.
The expected behavior is for the fail-safe to return an error if the execution of the given command returns an error. The intention is that users writing such script would be able to output a blank lines in case there is nothing to probe, but still remain aware of issues during the execution of the command. The fail-safe ignores errors pertaining to absent devices due to its nature. This does not mean that it should ignore all errors and try to keep on going while everything else is on fire. The contract with the user is that "blank line" without other errors means "absent device". Garbled output or return code != 0 means runtime error and should be thrown to the user / application.
The fix changes the return value to be -ENODEV for this sub device in the two cases. By this way, failsafe tries to parse this sub device parameter by exec method until the output is correct.
The issue is that this portion of the code will be heavily modified anyway. The errno handling is erroneous and must be fixed, which is in conflict with your patch. I will send the intended fix shortly, referencing this patch and the issue your highlighted, but both patch won't be compatible.
quoted hunk ↗ jump to hunk
Fixes: a0194d828100 ("net/failsafe: add flexible device definition") Fixes: 35ffe4208140 ("net/failsafe: fix missing pclose after popen") Cc: stable@dpdk.org Signed-off-by: Matan Azrad <redacted> --- drivers/net/failsafe/failsafe_args.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)diff --git a/drivers/net/failsafe/failsafe_args.c b/drivers/net/failsafe/failsafe_args.c index 645c885..61c55df 100644 --- a/drivers/net/failsafe/failsafe_args.c +++ b/drivers/net/failsafe/failsafe_args.c@@ -157,12 +157,16 @@ fs_execute_cmd(struct sub_device *sdev, char *cmdline) ret = fs_parse_device(sdev, output); if (ret) { ERROR("Parsing device '%s' failed", output); + ret = -ENODEV; goto ret_pclose; } ret_pclose: pclose_ret = pclose(fp); if (pclose_ret) { - pclose_ret = errno; + if (errno == 0) + errno = -(pclose_ret = ret); + else + pclose_ret = errno; ERROR("pclose: %s", strerror(errno)); errno = old_err; return pclose_ret;-- 2.7.4
Best regards, -- Gaëtan Rivet 6WIND