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Re: [PATCH v2] Check and report for incomplete 'global' option format
From: |
Markus Armbruster |
Subject: |
Re: [PATCH v2] Check and report for incomplete 'global' option format |
Date: |
Tue, 15 Feb 2022 10:30:18 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) |
Rohit Kumar <rohit.kumar3@nutanix.com> writes:
> Qemu might crash when provided incomplete '-global' option.
> For example:
> qemu-system-x86_64 -global driver=isa-fdc
> qemu-system-x86_64: ../../devel/qemu/qapi/string-input-visitor.c:394:
> string_input_visitor_new: Assertion `str' failed.
> Aborted (core dumped)
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/604
The original qemu_global_option() only ever created QemuOpts with all
three options present. Code consuming these QemuOpts relies on this
invariant. Commit 3751d7c43f "vl: allow full-blown QemuOpts syntax for
-global" (v2.4.0) wrecked it.
Let's point to the root cause:
Fixes: 3751d7c43f795b45ffdb9429cfb09c6beea55c68
> Signed-off-by: Rohit Kumar <rohit.kumar3@nutanix.com>
> ---
> diff to v1:
> - Removed '\n' from error log message.
>
> softmmu/qdev-monitor.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
> index 01f3834db5..51b33caeca 100644
> --- a/softmmu/qdev-monitor.c
> +++ b/softmmu/qdev-monitor.c
> @@ -1020,6 +1020,7 @@ int qemu_global_option(const char *str)
> char driver[64], property[64];
> QemuOpts *opts;
> int rc, offset;
> + Error *err = NULL;
>
> rc = sscanf(str, "%63[^.=].%63[^=]%n", driver, property, &offset);
> if (rc == 2 && str[offset] == '=') {
> @@ -1031,7 +1032,12 @@ int qemu_global_option(const char *str)
> }
>
> opts = qemu_opts_parse_noisily(&qemu_global_opts, str, false);
> - if (!opts) {
> + if (!opts || !qemu_opt_get(opts, "driver") ||
> !qemu_opt_get(opts,"property") ||
> + !qemu_opt_get(opts, "value")) {
> + error_setg(&err, "Invalid 'global' option format! "
> + "Use -global <driver>.<property>=<value> or "
> + "-global driver=driver,property=property,value=value");
> + error_report_err(err);
> return -1;
> }
This fix isn't quite right.
When qemu_opts_parse_noisily() fails, it reports an error and returns
null. Your patch reports a second error then. Reproducer:
$ qemu-system-x86_64 -global =
qemu-system-x86_64: -global =: Invalid parameter ''
qemu-system-x86_64: -global =: Invalid 'global' option format! Use -global
<driver>.<property>=<value> or -global
driver=driver,property=property,value=value
You should do something like
opts = qemu_opts_parse_noisily(&qemu_global_opts, str, false);
if (!opts) {
return -1;
}
if (!qemu_opt_get(opts, "driver")
|| !qemu_opt_get(opts, "property")
|| !qemu_opt_get(opts, "value")) {
error_report("options 'driver', 'property', and 'value'"
" are required');
return -1;
}