| Message ID | 20210903110702.588291-3-philmd@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | glib: Replace g_memdup() by g_memdup2_qemu() | expand |
On Fri, Sep 03, 2021 at 01:06:36PM +0200, Philippe Mathieu-Daudé wrote: > When experimenting raising GLIB_VERSION_MIN_REQUIRED to 2.68 > (Fedora 34 provides GLib 2.68.1) we get: > > hw/virtio/virtio-crypto.c:245:24: error: 'g_memdup' is deprecated: Use 'g_memdup2' instead [-Werror,-Wdeprecated-declarations] > ... > > g_memdup() has been updated by g_memdup2() to fix eventual security > issues (size argument is 32-bit and could be truncated / wrapping). > GLib recommends to copy their static inline version of g_memdup2(): > https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2-now/5538 > > Our glib-compat.h provides a comment explaining how to deal with > these deprecated declarations (see commit e71e8cc0355 > "glib: enforce the minimum required version and warn about old APIs"). > > Following this comment suggestion, implement the g_memdup2_qemu() > wrapper to g_memdup2(), and use the safer equivalent inlined when > we are using pre-2.68 GLib. > > Reported-by: Eric Blake <eblake@redhat.com> > Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> > --- > include/glib-compat.h | 36 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 36 insertions(+) > > diff --git a/include/glib-compat.h b/include/glib-compat.h > index 9e95c888f54..6577d9ab393 100644 > --- a/include/glib-compat.h > +++ b/include/glib-compat.h > @@ -68,6 +68,42 @@ > * without generating warnings. > */ > > +/* > + * g_memdup2_qemu: > + * @mem: (nullable): the memory to copy. > + * @byte_size: the number of bytes to copy. > + * > + * Allocates @byte_size bytes of memory, and copies @byte_size bytes into it > + * from @mem. If @mem is %NULL it returns %NULL. > + * > + * This replaces g_memdup(), which was prone to integer overflows when > + * converting the argument from a #gsize to a #guint. > + * > + * This static inline version is a backport of the new public API from > + * GLib 2.68, kept internal to GLib for backport to older stable releases. > + * See https://gitlab.gnome.org/GNOME/glib/-/issues/2319. > + * > + * Returns: (nullable): a pointer to the newly-allocated copy of the memory, > + * or %NULL if @mem is %NULL. > + */ > +static inline gpointer g_memdup2_qemu(gconstpointer mem, gsize byte_size) > +{ > +#if GLIB_CHECK_VERSION(2, 68, 0) > + return g_memdup2(mem, byte_size); > +#else > + gpointer new_mem; > + > + if (mem && byte_size != 0) { > + new_mem = g_malloc(byte_size); > + memcpy(new_mem, mem, byte_size); > + } else { > + new_mem = NULL; > + } > + > + return new_mem; > +#endif > +} Close, but you missed the final piece of the puzzle #define g_memdup2(a) g_memdup2_qemu(a) Such that in all following patches you can use the normal "g_memdup2" API. This means when we later update min glib, we just delete the compat code here, and the callers don't need updates. Regards, Daniel
03.09.2021 14:16, Daniel P. Berrangé wrote: > On Fri, Sep 03, 2021 at 01:06:36PM +0200, Philippe Mathieu-Daudé wrote: >> When experimenting raising GLIB_VERSION_MIN_REQUIRED to 2.68 >> (Fedora 34 provides GLib 2.68.1) we get: >> >> hw/virtio/virtio-crypto.c:245:24: error: 'g_memdup' is deprecated: Use 'g_memdup2' instead [-Werror,-Wdeprecated-declarations] >> ... >> >> g_memdup() has been updated by g_memdup2() to fix eventual security >> issues (size argument is 32-bit and could be truncated / wrapping). >> GLib recommends to copy their static inline version of g_memdup2(): >> https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2-now/5538 >> >> Our glib-compat.h provides a comment explaining how to deal with >> these deprecated declarations (see commit e71e8cc0355 >> "glib: enforce the minimum required version and warn about old APIs"). >> >> Following this comment suggestion, implement the g_memdup2_qemu() >> wrapper to g_memdup2(), and use the safer equivalent inlined when >> we are using pre-2.68 GLib. >> >> Reported-by: Eric Blake <eblake@redhat.com> >> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> >> --- >> include/glib-compat.h | 36 ++++++++++++++++++++++++++++++++++++ >> 1 file changed, 36 insertions(+) >> >> diff --git a/include/glib-compat.h b/include/glib-compat.h >> index 9e95c888f54..6577d9ab393 100644 >> --- a/include/glib-compat.h >> +++ b/include/glib-compat.h >> @@ -68,6 +68,42 @@ >> * without generating warnings. >> */ >> >> +/* >> + * g_memdup2_qemu: >> + * @mem: (nullable): the memory to copy. >> + * @byte_size: the number of bytes to copy. >> + * >> + * Allocates @byte_size bytes of memory, and copies @byte_size bytes into it >> + * from @mem. If @mem is %NULL it returns %NULL. >> + * >> + * This replaces g_memdup(), which was prone to integer overflows when >> + * converting the argument from a #gsize to a #guint. >> + * >> + * This static inline version is a backport of the new public API from >> + * GLib 2.68, kept internal to GLib for backport to older stable releases. >> + * See https://gitlab.gnome.org/GNOME/glib/-/issues/2319. >> + * >> + * Returns: (nullable): a pointer to the newly-allocated copy of the memory, >> + * or %NULL if @mem is %NULL. >> + */ >> +static inline gpointer g_memdup2_qemu(gconstpointer mem, gsize byte_size) >> +{ >> +#if GLIB_CHECK_VERSION(2, 68, 0) >> + return g_memdup2(mem, byte_size); >> +#else >> + gpointer new_mem; >> + >> + if (mem && byte_size != 0) { >> + new_mem = g_malloc(byte_size); >> + memcpy(new_mem, mem, byte_size); >> + } else { >> + new_mem = NULL; >> + } >> + >> + return new_mem; >> +#endif >> +} > > Close, but you missed the final piece of the puzzle > > #define g_memdup2(a) g_memdup2_qemu(a) > > > Such that in all following patches you can use the normal "g_memdup2" > API. This means when we later update min glib, we just delete the > compat code here, and the callers don't need updates. > That was most probably already discussed, so sorry my question: Why we can't just do #if ! GLIB_CHECK_VERSION(2, 68, 0) static inline gpointer g_memdup2(gconstpointer mem, gsize byte_size) { gpointer new_mem; if (mem && byte_size != 0) { new_mem = g_malloc(byte_size); memcpy(new_mem, mem, byte_size); } else { new_mem = NULL; } return new_mem; } #endif ?
On Fri, Sep 03, 2021 at 02:51:21PM +0300, Vladimir Sementsov-Ogievskiy wrote: > That was most probably already discussed, so sorry my question: > > Why we can't just do > > #if ! GLIB_CHECK_VERSION(2, 68, 0) > static inline gpointer g_memdup2(gconstpointer mem, gsize byte_size) > { > gpointer new_mem; > > if (mem && byte_size != 0) { > new_mem = g_malloc(byte_size); > memcpy(new_mem, mem, byte_size); > } else { > new_mem = NULL; > } > > return new_mem; > } > #endif > > ? This doesn't play with GLIB_VERSION_MAX_ALLOWED - any use of g_memdup2 will trigger compile warnings since we're using an API that only exists in a glib version newer than our declared baseline. The inline wrapper + macro is a trick that lets us backport new features, while avoiding the compile warnings. This is documented in the include/glib-compat.h file that Philippe is modifying. Regards, Daniel
03.09.2021 14:56, Daniel P. Berrangé wrote: > On Fri, Sep 03, 2021 at 02:51:21PM +0300, Vladimir Sementsov-Ogievskiy wrote: >> That was most probably already discussed, so sorry my question: >> >> Why we can't just do >> >> #if ! GLIB_CHECK_VERSION(2, 68, 0) >> static inline gpointer g_memdup2(gconstpointer mem, gsize byte_size) >> { >> gpointer new_mem; >> >> if (mem && byte_size != 0) { >> new_mem = g_malloc(byte_size); >> memcpy(new_mem, mem, byte_size); >> } else { >> new_mem = NULL; >> } >> >> return new_mem; >> } >> #endif >> >> ? > > This doesn't play with GLIB_VERSION_MAX_ALLOWED - any use of > g_memdup2 will trigger compile warnings since we're using an > API that only exists in a glib version newer than our declared > baseline. > > The inline wrapper + macro is a trick that lets us backport > new features, while avoiding the compile warnings. Ah right, with macro, compiler doesn't see g_memdup2() invocations in code. Thanks! > > This is documented in the include/glib-compat.h file that Philippe > is modifying. > > Regards, > Daniel >
On 9/3/21 1:16 PM, Daniel P. Berrangé wrote: > On Fri, Sep 03, 2021 at 01:06:36PM +0200, Philippe Mathieu-Daudé wrote: >> When experimenting raising GLIB_VERSION_MIN_REQUIRED to 2.68 >> (Fedora 34 provides GLib 2.68.1) we get: >> >> hw/virtio/virtio-crypto.c:245:24: error: 'g_memdup' is deprecated: Use 'g_memdup2' instead [-Werror,-Wdeprecated-declarations] >> ... >> >> g_memdup() has been updated by g_memdup2() to fix eventual security >> issues (size argument is 32-bit and could be truncated / wrapping). >> GLib recommends to copy their static inline version of g_memdup2(): >> https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2-now/5538 >> >> Our glib-compat.h provides a comment explaining how to deal with >> these deprecated declarations (see commit e71e8cc0355 >> "glib: enforce the minimum required version and warn about old APIs"). >> >> Following this comment suggestion, implement the g_memdup2_qemu() >> wrapper to g_memdup2(), and use the safer equivalent inlined when >> we are using pre-2.68 GLib. >> >> Reported-by: Eric Blake <eblake@redhat.com> >> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> >> --- >> include/glib-compat.h | 36 ++++++++++++++++++++++++++++++++++++ >> 1 file changed, 36 insertions(+) >> >> diff --git a/include/glib-compat.h b/include/glib-compat.h >> index 9e95c888f54..6577d9ab393 100644 >> --- a/include/glib-compat.h >> +++ b/include/glib-compat.h >> @@ -68,6 +68,42 @@ >> * without generating warnings. >> */ >> >> +/* >> + * g_memdup2_qemu: >> + * @mem: (nullable): the memory to copy. >> + * @byte_size: the number of bytes to copy. >> + * >> + * Allocates @byte_size bytes of memory, and copies @byte_size bytes into it >> + * from @mem. If @mem is %NULL it returns %NULL. >> + * >> + * This replaces g_memdup(), which was prone to integer overflows when >> + * converting the argument from a #gsize to a #guint. >> + * >> + * This static inline version is a backport of the new public API from >> + * GLib 2.68, kept internal to GLib for backport to older stable releases. >> + * See https://gitlab.gnome.org/GNOME/glib/-/issues/2319. >> + * >> + * Returns: (nullable): a pointer to the newly-allocated copy of the memory, >> + * or %NULL if @mem is %NULL. >> + */ >> +static inline gpointer g_memdup2_qemu(gconstpointer mem, gsize byte_size) >> +{ >> +#if GLIB_CHECK_VERSION(2, 68, 0) >> + return g_memdup2(mem, byte_size); >> +#else >> + gpointer new_mem; >> + >> + if (mem && byte_size != 0) { >> + new_mem = g_malloc(byte_size); >> + memcpy(new_mem, mem, byte_size); >> + } else { >> + new_mem = NULL; >> + } >> + >> + return new_mem; >> +#endif >> +} > > Close, but you missed the final piece of the puzzle > > #define g_memdup2(a) g_memdup2_qemu(a) Doh :/ > Such that in all following patches you can use the normal "g_memdup2" > API. This means when we later update min glib, we just delete the > compat code here, and the callers don't need updates. Painful rebase in perspective...
diff --git a/include/glib-compat.h b/include/glib-compat.h index 9e95c888f54..6577d9ab393 100644 --- a/include/glib-compat.h +++ b/include/glib-compat.h @@ -68,6 +68,42 @@ * without generating warnings. */ +/* + * g_memdup2_qemu: + * @mem: (nullable): the memory to copy. + * @byte_size: the number of bytes to copy. + * + * Allocates @byte_size bytes of memory, and copies @byte_size bytes into it + * from @mem. If @mem is %NULL it returns %NULL. + * + * This replaces g_memdup(), which was prone to integer overflows when + * converting the argument from a #gsize to a #guint. + * + * This static inline version is a backport of the new public API from + * GLib 2.68, kept internal to GLib for backport to older stable releases. + * See https://gitlab.gnome.org/GNOME/glib/-/issues/2319. + * + * Returns: (nullable): a pointer to the newly-allocated copy of the memory, + * or %NULL if @mem is %NULL. + */ +static inline gpointer g_memdup2_qemu(gconstpointer mem, gsize byte_size) +{ +#if GLIB_CHECK_VERSION(2, 68, 0) + return g_memdup2(mem, byte_size); +#else + gpointer new_mem; + + if (mem && byte_size != 0) { + new_mem = g_malloc(byte_size); + memcpy(new_mem, mem, byte_size); + } else { + new_mem = NULL; + } + + return new_mem; +#endif +} + #if defined(G_OS_UNIX) /* * Note: The fallback implementation is not MT-safe, and it returns a copy of
When experimenting raising GLIB_VERSION_MIN_REQUIRED to 2.68 (Fedora 34 provides GLib 2.68.1) we get: hw/virtio/virtio-crypto.c:245:24: error: 'g_memdup' is deprecated: Use 'g_memdup2' instead [-Werror,-Wdeprecated-declarations] ... g_memdup() has been updated by g_memdup2() to fix eventual security issues (size argument is 32-bit and could be truncated / wrapping). GLib recommends to copy their static inline version of g_memdup2(): https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2-now/5538 Our glib-compat.h provides a comment explaining how to deal with these deprecated declarations (see commit e71e8cc0355 "glib: enforce the minimum required version and warn about old APIs"). Following this comment suggestion, implement the g_memdup2_qemu() wrapper to g_memdup2(), and use the safer equivalent inlined when we are using pre-2.68 GLib. Reported-by: Eric Blake <eblake@redhat.com> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> --- include/glib-compat.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+)