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[Qemu-devel] [PATCH] cutils: Assert in-range base for string-to-integer conversions

Eric Blake posted 1 patch 5 years, 4 months ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/20181206151856.77503-1-eblake@redhat.com
util/cutils.c | 8 ++++++++
1 file changed, 8 insertions(+)
[Qemu-devel] [PATCH] cutils: Assert in-range base for string-to-integer conversions
Posted by Eric Blake 5 years, 4 months ago 
POSIX states that the value of endptr is unspecified if strtol()
fails with EINVAL due to an invalid base argument.  Since none of
the callers to check_strtox_error() initialized endptr, we could
end up propagating uninitialized data back to a caller on error.
However, passing an out-of-range base is already a sign of poor
programming, so let's just assert that base is in range, at which
point check_strtox_error() can be tightened to assert that it is
receiving an initialized ep that points somewhere within the
caller's original string, regardless of whether strto*() succeeded
or failed with ERANGE.

Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---

Also tested that this does not negatively impact David's pending
additions of qemu_strtod{,_finite}().  Thus:
Based-on: <20181121164421.20780-1-david@redhat.com>

 util/cutils.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/util/cutils.c b/util/cutils.c
index 91930d1bbeb..e098debdc0c 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -278,6 +278,7 @@ int qemu_strtosz_metric(const char *nptr, const char **end, uint64_t *result)
 static int check_strtox_error(const char *nptr, char *ep,
                               const char **endptr, int libc_errno)
 {
+    assert(ep >= nptr);
     if (endptr) {
         *endptr = ep;
     }
@@ -325,6 +326,7 @@ int qemu_strtoi(const char *nptr, const char **endptr, int base,
     char *ep;
     long long lresult;

+    assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
         if (endptr) {
             *endptr = nptr;
@@ -377,6 +379,7 @@ int qemu_strtoui(const char *nptr, const char **endptr, int base,
     char *ep;
     long long lresult;

+    assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
         if (endptr) {
             *endptr = nptr;
@@ -433,6 +436,7 @@ int qemu_strtol(const char *nptr, const char **endptr, int base,
 {
     char *ep;

+    assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
         if (endptr) {
             *endptr = nptr;
@@ -475,6 +479,7 @@ int qemu_strtoul(const char *nptr, const char **endptr, int base,
 {
     char *ep;

+    assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
         if (endptr) {
             *endptr = nptr;
@@ -502,6 +507,7 @@ int qemu_strtoi64(const char *nptr, const char **endptr, int base,
 {
     char *ep;

+    assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
         if (endptr) {
             *endptr = nptr;
@@ -525,6 +531,7 @@ int qemu_strtou64(const char *nptr, const char **endptr, int base,
 {
     char *ep;

+    assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
         if (endptr) {
             *endptr = nptr;
@@ -657,6 +664,7 @@ int parse_uint(const char *s, unsigned long long *value, char **endptr,
     char *endp = (char *)s;
     unsigned long long val = 0;

+    assert((unsigned) base <= 36 && base != 1);
     if (!s) {
         r = -EINVAL;
         goto out;
-- 
2.17.2
Re: [Qemu-devel] [PATCH] cutils: Assert in-range base for string-to-integer conversions
Posted by Philippe Mathieu-Daudé 5 years, 4 months ago 
On 12/6/18 4:18 PM, Eric Blake wrote:
> POSIX states that the value of endptr is unspecified if strtol()
> fails with EINVAL due to an invalid base argument.  Since none of
> the callers to check_strtox_error() initialized endptr, we could
> end up propagating uninitialized data back to a caller on error.
> However, passing an out-of-range base is already a sign of poor
> programming, so let's just assert that base is in range, at which
> point check_strtox_error() can be tightened to assert that it is
> receiving an initialized ep that points somewhere within the
> caller's original string, regardless of whether strto*() succeeded
> or failed with ERANGE.
> 
> Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
> 
> Also tested that this does not negatively impact David's pending
> additions of qemu_strtod{,_finite}().  Thus:
> Based-on: <20181121164421.20780-1-david@redhat.com>
> 
>  util/cutils.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/util/cutils.c b/util/cutils.c
> index 91930d1bbeb..e098debdc0c 100644
> --- a/util/cutils.c
> +++ b/util/cutils.c
> @@ -278,6 +278,7 @@ int qemu_strtosz_metric(const char *nptr, const char **end, uint64_t *result)
>  static int check_strtox_error(const char *nptr, char *ep,
>                                const char **endptr, int libc_errno)
>  {
> +    assert(ep >= nptr);
>      if (endptr) {
>          *endptr = ep;
>      }
> @@ -325,6 +326,7 @@ int qemu_strtoi(const char *nptr, const char **endptr, int base,
>      char *ep;
>      long long lresult;
> 
> +    assert((unsigned) base <= 36 && base != 1);
>      if (!nptr) {
>          if (endptr) {
>              *endptr = nptr;
> @@ -377,6 +379,7 @@ int qemu_strtoui(const char *nptr, const char **endptr, int base,
>      char *ep;
>      long long lresult;
> 
> +    assert((unsigned) base <= 36 && base != 1);
>      if (!nptr) {
>          if (endptr) {
>              *endptr = nptr;
> @@ -433,6 +436,7 @@ int qemu_strtol(const char *nptr, const char **endptr, int base,
>  {
>      char *ep;
> 
> +    assert((unsigned) base <= 36 && base != 1);
>      if (!nptr) {
>          if (endptr) {
>              *endptr = nptr;
> @@ -475,6 +479,7 @@ int qemu_strtoul(const char *nptr, const char **endptr, int base,
>  {
>      char *ep;
> 
> +    assert((unsigned) base <= 36 && base != 1);
>      if (!nptr) {
>          if (endptr) {
>              *endptr = nptr;
> @@ -502,6 +507,7 @@ int qemu_strtoi64(const char *nptr, const char **endptr, int base,
>  {
>      char *ep;
> 
> +    assert((unsigned) base <= 36 && base != 1);
>      if (!nptr) {
>          if (endptr) {
>              *endptr = nptr;
> @@ -525,6 +531,7 @@ int qemu_strtou64(const char *nptr, const char **endptr, int base,
>  {
>      char *ep;
> 
> +    assert((unsigned) base <= 36 && base != 1);
>      if (!nptr) {
>          if (endptr) {
>              *endptr = nptr;
> @@ -657,6 +664,7 @@ int parse_uint(const char *s, unsigned long long *value, char **endptr,
>      char *endp = (char *)s;
>      unsigned long long val = 0;
> 
> +    assert((unsigned) base <= 36 && base != 1);
>      if (!s) {
>          r = -EINVAL;
>          goto out;
> 

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Re: [Qemu-devel] [Qemu-trivial] [PATCH] cutils: Assert in-range base for string-to-integer conversions
Posted by Laurent Vivier 5 years, 4 months ago 
Le 06/12/2018 à 16:18, Eric Blake a écrit :
> POSIX states that the value of endptr is unspecified if strtol()
> fails with EINVAL due to an invalid base argument.  Since none of
> the callers to check_strtox_error() initialized endptr, we could
> end up propagating uninitialized data back to a caller on error.
> However, passing an out-of-range base is already a sign of poor
> programming, so let's just assert that base is in range, at which
> point check_strtox_error() can be tightened to assert that it is
> receiving an initialized ep that points somewhere within the
> caller's original string, regardless of whether strto*() succeeded
> or failed with ERANGE.
> 
> Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
> 
> Also tested that this does not negatively impact David's pending
> additions of qemu_strtod{,_finite}().  Thus:
> Based-on: <20181121164421.20780-1-david@redhat.com>
> 
>  util/cutils.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 

Applied to my trivial-patches branch.

Thanks,
Laurent
Re: [Qemu-devel] [PATCH] cutils: Assert in-range base for string-to-integer conversions
Posted by Markus Armbruster 5 years, 4 months ago 
Eric Blake <eblake@redhat.com> writes:

> POSIX states that the value of endptr is unspecified if strtol()
> fails with EINVAL due to an invalid base argument.  Since none of
> the callers to check_strtox_error() initialized endptr, we could
> end up propagating uninitialized data back to a caller on error.
> However, passing an out-of-range base is already a sign of poor
> programming, so let's just assert that base is in range, at which
> point check_strtox_error() can be tightened to assert that it is
> receiving an initialized ep that points somewhere within the
> caller's original string, regardless of whether strto*() succeeded
> or failed with ERANGE.
>
> Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Signed-off-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Markus Armbruster <armbru@redhat.com>
Re: [Qemu-devel] [Qemu-trivial] [PATCH] cutils: Assert in-range base for string-to-integer conversions
Posted by Laurent Vivier 5 years, 4 months ago 
Le 06/12/2018 à 16:18, Eric Blake a écrit :
> POSIX states that the value of endptr is unspecified if strtol()
> fails with EINVAL due to an invalid base argument.  Since none of
> the callers to check_strtox_error() initialized endptr, we could
> end up propagating uninitialized data back to a caller on error.
> However, passing an out-of-range base is already a sign of poor
> programming, so let's just assert that base is in range, at which
> point check_strtox_error() can be tightened to assert that it is
> receiving an initialized ep that points somewhere within the
> caller's original string, regardless of whether strto*() succeeded
> or failed with ERANGE.
> 
> Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
> 
> Also tested that this does not negatively impact David's pending
> additions of qemu_strtod{,_finite}().  Thus:
> Based-on: <20181121164421.20780-1-david@redhat.com>
> 
>  util/cutils.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/util/cutils.c b/util/cutils.c
> index 91930d1bbeb..e098debdc0c 100644
> --- a/util/cutils.c
> +++ b/util/cutils.c
> @@ -278,6 +278,7 @@ int qemu_strtosz_metric(const char *nptr, const char **end, uint64_t *result)
>  static int check_strtox_error(const char *nptr, char *ep,
>                                const char **endptr, int libc_errno)
>  {
> +    assert(ep >= nptr);
>      if (endptr) {
>          *endptr = ep;
>      }
> @@ -325,6 +326,7 @@ int qemu_strtoi(const char *nptr, const char **endptr, int base,
>      char *ep;
>      long long lresult;
> 
> +    assert((unsigned) base <= 36 && base != 1);

If you want to play with type, I think you can do:

   assert((unsigned)(base - 2) <= 34)

Thanks,
Laurent
Re: [Qemu-devel] [Qemu-trivial] [PATCH] cutils: Assert in-range base for string-to-integer conversions
Posted by Laurent Vivier 5 years, 4 months ago 
Le 06/12/2018 à 17:40, Laurent Vivier a écrit :
> Le 06/12/2018 à 16:18, Eric Blake a écrit :
>> POSIX states that the value of endptr is unspecified if strtol()
>> fails with EINVAL due to an invalid base argument.  Since none of
>> the callers to check_strtox_error() initialized endptr, we could
>> end up propagating uninitialized data back to a caller on error.
>> However, passing an out-of-range base is already a sign of poor
>> programming, so let's just assert that base is in range, at which
>> point check_strtox_error() can be tightened to assert that it is
>> receiving an initialized ep that points somewhere within the
>> caller's original string, regardless of whether strto*() succeeded
>> or failed with ERANGE.
>>
>> Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>> ---
>>
>> Also tested that this does not negatively impact David's pending
>> additions of qemu_strtod{,_finite}().  Thus:
>> Based-on: <20181121164421.20780-1-david@redhat.com>
>>
>>  util/cutils.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/util/cutils.c b/util/cutils.c
>> index 91930d1bbeb..e098debdc0c 100644
>> --- a/util/cutils.c
>> +++ b/util/cutils.c
>> @@ -278,6 +278,7 @@ int qemu_strtosz_metric(const char *nptr, const char **end, uint64_t *result)
>>  static int check_strtox_error(const char *nptr, char *ep,
>>                                const char **endptr, int libc_errno)
>>  {
>> +    assert(ep >= nptr);
>>      if (endptr) {
>>          *endptr = ep;
>>      }
>> @@ -325,6 +326,7 @@ int qemu_strtoi(const char *nptr, const char **endptr, int base,
>>      char *ep;
>>      long long lresult;
>>
>> +    assert((unsigned) base <= 36 && base != 1);
> 
> If you want to play with type, I think you can do:
> 
>    assert((unsigned)(base - 2) <= 34)

oops, no, '0' is a valid case. Forgive this...

Laurent

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