[PATCH 0/2] Small fuzzer-related changes

[PATCH 0/2] Small fuzzer-related changes

[Alexander Bulekov]

Fix outdated paths in documentation and log some useful information.

Alexander Bulekov (2):
  docs/fuzz: fix pre-meson path
  fuzz: log the arguments used to initialize QEMU

 docs/devel/fuzzing.rst  |  5 ++---
 tests/qtest/fuzz/fuzz.c | 11 ++++++++++-
 2 files changed, 12 insertions(+), 4 deletions(-)

-- 
2.28.0

[PATCH 1/2] docs/fuzz: fix pre-meson path

[Alexander Bulekov]

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
---
 docs/devel/fuzzing.rst | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/docs/devel/fuzzing.rst b/docs/devel/fuzzing.rst
index 8792358854..b9bb07988b 100644
--- a/docs/devel/fuzzing.rst
+++ b/docs/devel/fuzzing.rst
@@ -119,7 +119,7 @@ Adding a new fuzzer
 
 Coverage over virtual devices can be improved by adding additional fuzzers.
 Fuzzers are kept in ``tests/qtest/fuzz/`` and should be added to
-``tests/qtest/fuzz/Makefile.include``
+``tests/qtest/fuzz/meson.build``
 
 Fuzzers can rely on both qtest and libqos to communicate with virtual devices.
 
@@ -128,8 +128,7 @@ Fuzzers can rely on both qtest and libqos to communicate with virtual devices.
 2. Write the fuzzing code using the libqtest/libqos API. See existing fuzzers
    for reference.
 
-3. Register the fuzzer in ``tests/fuzz/Makefile.include`` by appending the
-   corresponding object to fuzz-obj-y
+3. Add the fuzzer to ``tests/qtest/fuzz/meson.build``.
 
 Fuzzers can be more-or-less thought of as special qtest programs which can
 modify the qtest commands and/or qtest command arguments based on inputs
-- 
2.28.0

[PATCH 2/2] fuzz: log the arguments used to initialize QEMU

[Alexander Bulekov]

This is useful for building reproducers. Instead checking the code or
the QEMU_FUZZ_ARGS, the arguments are at the top of the crash log.

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
---
 tests/qtest/fuzz/fuzz.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tests/qtest/fuzz/fuzz.c b/tests/qtest/fuzz/fuzz.c
index 238866a037..496d11a231 100644
--- a/tests/qtest/fuzz/fuzz.c
+++ b/tests/qtest/fuzz/fuzz.c
@@ -159,6 +159,8 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
     char *target_name;
     const char *bindir;
     char *datadir;
+    GString *cmd_line;
+    gchar *pretty_cmd_line;
     bool serialize = false;
 
     /* Initialize qgraph and modules */
@@ -217,7 +219,7 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
     }
 
     /* Run QEMU's softmmu main with the fuzz-target dependent arguments */
-    GString *cmd_line = fuzz_target->get_init_cmdline(fuzz_target);
+    cmd_line = fuzz_target->get_init_cmdline(fuzz_target);
     g_string_append_printf(cmd_line, " %s -qtest /dev/null ",
                            getenv("QTEST_LOG") ? "" : "-qtest-log none");
 
@@ -226,6 +228,13 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
     wordexp(cmd_line->str, &result, 0);
     g_string_free(cmd_line, true);
 
+    if (getenv("QTEST_LOG")) {
+        pretty_cmd_line  = g_strjoinv(" ", result.we_wordv + 1);
+        printf("Starting %s with Arguments: %s\n",
+                result.we_wordv[0], pretty_cmd_line);
+        g_free(pretty_cmd_line);
+    }
+
     qemu_init(result.we_wordc, result.we_wordv, NULL);
 
     /* re-enable the rcu atfork, which was previously disabled in qemu_init */
-- 
2.28.0

Re: [PATCH 1/2] docs/fuzz: fix pre-meson path

[Thomas Huth]

On 17/01/2021 21.10, Alexander Bulekov wrote:
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> ---
>   docs/devel/fuzzing.rst | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/docs/devel/fuzzing.rst b/docs/devel/fuzzing.rst
> index 8792358854..b9bb07988b 100644
> --- a/docs/devel/fuzzing.rst
> +++ b/docs/devel/fuzzing.rst
> @@ -119,7 +119,7 @@ Adding a new fuzzer
>   
>   Coverage over virtual devices can be improved by adding additional fuzzers.
>   Fuzzers are kept in ``tests/qtest/fuzz/`` and should be added to
> -``tests/qtest/fuzz/Makefile.include``
> +``tests/qtest/fuzz/meson.build``
>   
>   Fuzzers can rely on both qtest and libqos to communicate with virtual devices.
>   
> @@ -128,8 +128,7 @@ Fuzzers can rely on both qtest and libqos to communicate with virtual devices.
>   2. Write the fuzzing code using the libqtest/libqos API. See existing fuzzers
>      for reference.
>   
> -3. Register the fuzzer in ``tests/fuzz/Makefile.include`` by appending the
> -   corresponding object to fuzz-obj-y
> +3. Add the fuzzer to ``tests/qtest/fuzz/meson.build``.
>   
>   Fuzzers can be more-or-less thought of as special qtest programs which can
>   modify the qtest commands and/or qtest command arguments based on inputs
> 

Reviewed-by: Thomas Huth <thuth@redhat.com>

Re: [PATCH 2/2] fuzz: log the arguments used to initialize QEMU

[Thomas Huth]

On 17/01/2021 21.10, Alexander Bulekov wrote:
> This is useful for building reproducers. Instead checking the code or
> the QEMU_FUZZ_ARGS, the arguments are at the top of the crash log.
> 
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> ---
>   tests/qtest/fuzz/fuzz.c | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/qtest/fuzz/fuzz.c b/tests/qtest/fuzz/fuzz.c
> index 238866a037..496d11a231 100644
> --- a/tests/qtest/fuzz/fuzz.c
> +++ b/tests/qtest/fuzz/fuzz.c
> @@ -159,6 +159,8 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
>       char *target_name;
>       const char *bindir;
>       char *datadir;
> +    GString *cmd_line;
> +    gchar *pretty_cmd_line;
>       bool serialize = false;
>   
>       /* Initialize qgraph and modules */
> @@ -217,7 +219,7 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
>       }
>   
>       /* Run QEMU's softmmu main with the fuzz-target dependent arguments */
> -    GString *cmd_line = fuzz_target->get_init_cmdline(fuzz_target);
> +    cmd_line = fuzz_target->get_init_cmdline(fuzz_target);
>       g_string_append_printf(cmd_line, " %s -qtest /dev/null ",
>                              getenv("QTEST_LOG") ? "" : "-qtest-log none");
>   
> @@ -226,6 +228,13 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
>       wordexp(cmd_line->str, &result, 0);
>       g_string_free(cmd_line, true);
>   
> +    if (getenv("QTEST_LOG")) {
> +        pretty_cmd_line  = g_strjoinv(" ", result.we_wordv + 1);
> +        printf("Starting %s with Arguments: %s\n",
> +                result.we_wordv[0], pretty_cmd_line);
> +        g_free(pretty_cmd_line);
> +    }
> +
>       qemu_init(result.we_wordc, result.we_wordv, NULL);
>   
>       /* re-enable the rcu atfork, which was previously disabled in qemu_init */
> 

Reviewed-by: Thomas Huth <thuth@redhat.com>

pending fuzzing patches (was Re: [PATCH 2/2] fuzz: log the arguments used to initialize QEMU)

[Paolo Bonzini]

On 17/01/21 21:10, Alexander Bulekov wrote:
> This is useful for building reproducers. Instead checking the code or
> the QEMU_FUZZ_ARGS, the arguments are at the top of the crash log.
> 
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> ---
>   tests/qtest/fuzz/fuzz.c | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/qtest/fuzz/fuzz.c b/tests/qtest/fuzz/fuzz.c
> index 238866a037..496d11a231 100644
> --- a/tests/qtest/fuzz/fuzz.c
> +++ b/tests/qtest/fuzz/fuzz.c
> @@ -159,6 +159,8 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
>       char *target_name;
>       const char *bindir;
>       char *datadir;
> +    GString *cmd_line;
> +    gchar *pretty_cmd_line;
>       bool serialize = false;
>   
>       /* Initialize qgraph and modules */
> @@ -217,7 +219,7 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
>       }
>   
>       /* Run QEMU's softmmu main with the fuzz-target dependent arguments */
> -    GString *cmd_line = fuzz_target->get_init_cmdline(fuzz_target);
> +    cmd_line = fuzz_target->get_init_cmdline(fuzz_target);
>       g_string_append_printf(cmd_line, " %s -qtest /dev/null ",
>                              getenv("QTEST_LOG") ? "" : "-qtest-log none");
>   
> @@ -226,6 +228,13 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
>       wordexp(cmd_line->str, &result, 0);
>       g_string_free(cmd_line, true);
>   
> +    if (getenv("QTEST_LOG")) {
> +        pretty_cmd_line  = g_strjoinv(" ", result.we_wordv + 1);
> +        printf("Starting %s with Arguments: %s\n",
> +                result.we_wordv[0], pretty_cmd_line);
> +        g_free(pretty_cmd_line);
> +    }
> +
>       qemu_init(result.we_wordc, result.we_wordv, NULL);
>   
>       /* re-enable the rcu atfork, which was previously disabled in qemu_init */
> 

Hi Alexander, can you send _me_ a pull request for all the pending 
fuzzing patches?  I haven't paid much attention, but I have seen 
external contributions and I have the feeling that they aren't being 
applied/reviewed promptly.

Paolo

Re: pending fuzzing patches (was Re: [PATCH 2/2] fuzz: log the arguments used to initialize QEMU)

[Thomas Huth]

On 18/01/2021 09.43, Paolo Bonzini wrote:
> On 17/01/21 21:10, Alexander Bulekov wrote:
>> This is useful for building reproducers. Instead checking the code or
>> the QEMU_FUZZ_ARGS, the arguments are at the top of the crash log.
>>
>> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
>> ---
>>   tests/qtest/fuzz/fuzz.c | 11 ++++++++++-
>>   1 file changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/tests/qtest/fuzz/fuzz.c b/tests/qtest/fuzz/fuzz.c
>> index 238866a037..496d11a231 100644
>> --- a/tests/qtest/fuzz/fuzz.c
>> +++ b/tests/qtest/fuzz/fuzz.c
>> @@ -159,6 +159,8 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char 
>> ***envp)
>>       char *target_name;
>>       const char *bindir;
>>       char *datadir;
>> +    GString *cmd_line;
>> +    gchar *pretty_cmd_line;
>>       bool serialize = false;
>>       /* Initialize qgraph and modules */
>> @@ -217,7 +219,7 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char 
>> ***envp)
>>       }
>>       /* Run QEMU's softmmu main with the fuzz-target dependent arguments */
>> -    GString *cmd_line = fuzz_target->get_init_cmdline(fuzz_target);
>> +    cmd_line = fuzz_target->get_init_cmdline(fuzz_target);
>>       g_string_append_printf(cmd_line, " %s -qtest /dev/null ",
>>                              getenv("QTEST_LOG") ? "" : "-qtest-log none");
>> @@ -226,6 +228,13 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, 
>> char ***envp)
>>       wordexp(cmd_line->str, &result, 0);
>>       g_string_free(cmd_line, true);
>> +    if (getenv("QTEST_LOG")) {
>> +        pretty_cmd_line  = g_strjoinv(" ", result.we_wordv + 1);
>> +        printf("Starting %s with Arguments: %s\n",
>> +                result.we_wordv[0], pretty_cmd_line);
>> +        g_free(pretty_cmd_line);
>> +    }
>> +
>>       qemu_init(result.we_wordc, result.we_wordv, NULL);
>>       /* re-enable the rcu atfork, which was previously disabled in 
>> qemu_init */
>>
> 
> Hi Alexander, can you send _me_ a pull request for all the pending fuzzing 
> patches?  I haven't paid much attention, but I have seen external 
> contributions and I have the feeling that they aren't being applied/reviewed 
> promptly.

I'm normally taking the fuzzing patches through the qtest tree (and also 
merged some contributions last week, see 22ec0c696fd28e and the following 
commits) ... which patch series that got missed did you have in mind?

Anyway, the amount of fuzzer patches seems to have increased during the last 
weeks, and I'm not very familiar with the fuzzing stuff and also sometimes I 
do not get CC:-ed on fuzzing patches, so it might make sense indeed that 
Alexander now gathers the fuzzing patches and starts sending pull requests 
for these. Alexander, do you want to have a try now?

  Thomas

Re: pending fuzzing patches (was Re: [PATCH 2/2] fuzz: log the arguments used to initialize QEMU)

[Paolo Bonzini]

On 18/01/21 10:30, Thomas Huth wrote:
>>
>> Hi Alexander, can you send _me_ a pull request for all the pending 
>> fuzzing patches?  I haven't paid much attention, but I have seen 
>> external contributions and I have the feeling that they aren't being 
>> applied/reviewed promptly.
> 
> I'm normally taking the fuzzing patches through the qtest tree (and also 
> merged some contributions last week, see 22ec0c696fd28e and the 
> following commits) ... which patch series that got missed did you have 
> in mind?

I was thinking mostly of "fuzz: improve crash case minimization" which I 
had lost track of, but that one has been merged.

Paolo

> Anyway, the amount of fuzzer patches seems to have increased during the 
> last weeks, and I'm not very familiar with the fuzzing stuff and also 
> sometimes I do not get CC:-ed on fuzzing patches, so it might make sense 
> indeed that Alexander now gathers the fuzzing patches and starts sending 
> pull requests for these. Alexander, do you want to have a try now?
> 
>   Thomas

Re: pending fuzzing patches (was Re: [PATCH 2/2] fuzz: log the arguments used to initialize QEMU)

[Alexander Bulekov]

On 210118 1030, Thomas Huth wrote:
> On 18/01/2021 09.43, Paolo Bonzini wrote:
> > On 17/01/21 21:10, Alexander Bulekov wrote:
> > > This is useful for building reproducers. Instead checking the code or
> > > the QEMU_FUZZ_ARGS, the arguments are at the top of the crash log.
> > > 
> > > Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> > > ---
> > >   tests/qtest/fuzz/fuzz.c | 11 ++++++++++-
> > >   1 file changed, 10 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/tests/qtest/fuzz/fuzz.c b/tests/qtest/fuzz/fuzz.c
> > > index 238866a037..496d11a231 100644
> > > --- a/tests/qtest/fuzz/fuzz.c
> > > +++ b/tests/qtest/fuzz/fuzz.c
> > > @@ -159,6 +159,8 @@ int LLVMFuzzerInitialize(int *argc, char
> > > ***argv, char ***envp)
> > >       char *target_name;
> > >       const char *bindir;
> > >       char *datadir;
> > > +    GString *cmd_line;
> > > +    gchar *pretty_cmd_line;
> > >       bool serialize = false;
> > >       /* Initialize qgraph and modules */
> > > @@ -217,7 +219,7 @@ int LLVMFuzzerInitialize(int *argc, char
> > > ***argv, char ***envp)
> > >       }
> > >       /* Run QEMU's softmmu main with the fuzz-target dependent arguments */
> > > -    GString *cmd_line = fuzz_target->get_init_cmdline(fuzz_target);
> > > +    cmd_line = fuzz_target->get_init_cmdline(fuzz_target);
> > >       g_string_append_printf(cmd_line, " %s -qtest /dev/null ",
> > >                              getenv("QTEST_LOG") ? "" : "-qtest-log none");
> > > @@ -226,6 +228,13 @@ int LLVMFuzzerInitialize(int *argc, char
> > > ***argv, char ***envp)
> > >       wordexp(cmd_line->str, &result, 0);
> > >       g_string_free(cmd_line, true);
> > > +    if (getenv("QTEST_LOG")) {
> > > +        pretty_cmd_line  = g_strjoinv(" ", result.we_wordv + 1);
> > > +        printf("Starting %s with Arguments: %s\n",
> > > +                result.we_wordv[0], pretty_cmd_line);
> > > +        g_free(pretty_cmd_line);
> > > +    }
> > > +
> > >       qemu_init(result.we_wordc, result.we_wordv, NULL);
> > >       /* re-enable the rcu atfork, which was previously disabled in
> > > qemu_init */
> > > 
> > 
> > Hi Alexander, can you send _me_ a pull request for all the pending
> > fuzzing patches?  I haven't paid much attention, but I have seen
> > external contributions and I have the feeling that they aren't being
> > applied/reviewed promptly.
> 
> I'm normally taking the fuzzing patches through the qtest tree (and also
> merged some contributions last week, see 22ec0c696fd28e and the following
> commits) ... which patch series that got missed did you have in mind?
> 
> Anyway, the amount of fuzzer patches seems to have increased during the last
> weeks, and I'm not very familiar with the fuzzing stuff and also sometimes I
> do not get CC:-ed on fuzzing patches, so it might make sense indeed that
> Alexander now gathers the fuzzing patches and starts sending pull requests
> for these. Alexander, do you want to have a try now?
> 

Sure - I'll wait for both remaining series to be fully reviewed. Then
I'll follow this: https://wiki.qemu.org/Contribute/SubmitAPullRequest
-Alex


>  Thomas
>