* [PATCH] libio: Fix oversized __io_vtables
@ 2023-09-08 19:55 Adam Jackson
2023-09-08 20:59 ` Florian Weimer
0 siblings, 1 reply; 5+ messages in thread
From: Adam Jackson @ 2023-09-08 19:55 UTC (permalink / raw)
To: libc-alpha
IO_VTABLES_LEN is the size of the struct array in bytes, not the number
of __IO_jump_t's in the array. Drops just under 384kb from .rodata on
LP64 machines.
Fixes: 3020f72618e ("libio: Remove the usage of __libc_IO_vtables")
Signed-off-by: Adam Jackson <ajax@redhat.com>
---
libio/vtables.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/libio/vtables.c b/libio/vtables.c
index 1d8ad612e94..34f7e15f1c2 100644
--- a/libio/vtables.c
+++ b/libio/vtables.c
@@ -18,10 +18,11 @@
#include <dlfcn.h>
#include <libioP.h>
#include <stdio.h>
#include <ldsodefs.h>
+#include <array_length.h>
#include <pointer_guard.h>
#include <libio-macros.h>
/* Both _IO_str_* and _IO_new_file functions are pulled into every link (from
stdio initialization). */
@@ -86,11 +87,11 @@
# pragma weak __wprintf_buffer_as_file_overflow
# pragma weak __wprintf_buffer_as_file_xsputn
#endif
-const struct _IO_jump_t __io_vtables[IO_VTABLES_LEN] attribute_relro =
+const struct _IO_jump_t __io_vtables[] attribute_relro =
{
/* _IO_str_jumps */
[IO_STR_JUMPS] =
{
JUMP_INIT_DUMMY,
@@ -483,10 +484,12 @@ const struct _IO_jump_t __io_vtables[IO_VTABLES_LEN] attribute_relro =
JUMP_INIT (showmanyc, _IO_default_showmanyc),
JUMP_INIT (imbue, _IO_default_imbue),
},
#endif
};
+_Static_assert (array_length (__io_vtables) == IO_VTABLES_NUM,
+ "initializer count");
#ifdef SHARED
void (*IO_accept_foreign_vtables) (void) attribute_hidden;
--
2.41.0
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] libio: Fix oversized __io_vtables
2023-09-08 19:55 [PATCH] libio: Fix oversized __io_vtables Adam Jackson
@ 2023-09-08 20:59 ` Florian Weimer
0 siblings, 0 replies; 5+ messages in thread
From: Florian Weimer @ 2023-09-08 20:59 UTC (permalink / raw)
To: Adam Jackson; +Cc: libc-alpha
* Adam Jackson:
> IO_VTABLES_LEN is the size of the struct array in bytes, not the number
> of __IO_jump_t's in the array. Drops just under 384kb from .rodata on
> LP64 machines.
>
> Fixes: 3020f72618e ("libio: Remove the usage of __libc_IO_vtables")
> Signed-off-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Tested-by: Florian Weimer <fweimer@redhat.com>
And applied. Thanks!
Florian
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] libio: Fix oversized __io_vtables
2023-09-08 11:20 ` Florian Weimer
@ 2023-09-08 19:54 ` Adam Jackson
0 siblings, 0 replies; 5+ messages in thread
From: Adam Jackson @ 2023-09-08 19:54 UTC (permalink / raw)
To: Florian Weimer; +Cc: libc-alpha
[-- Attachment #1: Type: text/plain, Size: 478 bytes --]
On Fri, Sep 8, 2023 at 7:20 AM Florian Weimer <fweimer@redhat.com> wrote:
Maybe use [] and
>
> _Static_assert (array_length (__io_vtables) == IO_VTABLES_NUM,
> "initializer count);
>
> after the definition?
>
> Let me know if you want to make this change. I've got a machine
> checkout that can build glibc on all supported architectures fairly
> quickly.
>
Sure. I'll send a new patch, I spotted a grammar-o in the commit message.
- ajax
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] libio: Fix oversized __io_vtables
2023-09-07 19:38 Adam Jackson
@ 2023-09-08 11:20 ` Florian Weimer
2023-09-08 19:54 ` Adam Jackson
0 siblings, 1 reply; 5+ messages in thread
From: Florian Weimer @ 2023-09-08 11:20 UTC (permalink / raw)
To: Adam Jackson; +Cc: libc-alpha
* Adam Jackson:
> IO_VTABLES_LEN is the expected size of the struct in bytes, not the
> number of __IO_jump_t's in the array. Drops just under 384kb from
> .rodata on LP64 machines.
Ouch, thanks for spotting this.
I think it's this Debian and Ubuntu bug:
djbdns: Fix for tests with new glibc 2.38
<https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1050371>
tinydns: allocation failures with glibc 2.38/s390x
<https://bugs.launchpad.net/ubuntu/+source/djbdns/+bug/2031909>
> Fixes: 3020f72618e ("libio: Remove the usage of __libc_IO_vtables")
> Signed-off-by: Adam Jackson <ajax@redhat.com>
> ---
> libio/vtables.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libio/vtables.c b/libio/vtables.c
> index 1d8ad612e94..7cb894d751d 100644
> --- a/libio/vtables.c
> +++ b/libio/vtables.c
> @@ -86,11 +86,11 @@
>
> # pragma weak __wprintf_buffer_as_file_overflow
> # pragma weak __wprintf_buffer_as_file_xsputn
> #endif
>
> -const struct _IO_jump_t __io_vtables[IO_VTABLES_LEN] attribute_relro =
> +const struct _IO_jump_t __io_vtables[IO_VTABLES_NUM] attribute_relro =
> {
> /* _IO_str_jumps */
> [IO_STR_JUMPS] =
> {
> JUMP_INIT_DUMMY,
Maybe use [] and
_Static_assert (array_length (__io_vtables) == IO_VTABLES_NUM,
"initializer count);
after the definition?
Let me know if you want to make this change. I've got a machine
checkout that can build glibc on all supported architectures fairly
quickly.
Thanks,
Florian
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] libio: Fix oversized __io_vtables
@ 2023-09-07 19:38 Adam Jackson
2023-09-08 11:20 ` Florian Weimer
0 siblings, 1 reply; 5+ messages in thread
From: Adam Jackson @ 2023-09-07 19:38 UTC (permalink / raw)
To: libc-alpha
IO_VTABLES_LEN is the expected size of the struct in bytes, not the
number of __IO_jump_t's in the array. Drops just under 384kb from
.rodata on LP64 machines.
Fixes: 3020f72618e ("libio: Remove the usage of __libc_IO_vtables")
Signed-off-by: Adam Jackson <ajax@redhat.com>
---
libio/vtables.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libio/vtables.c b/libio/vtables.c
index 1d8ad612e94..7cb894d751d 100644
--- a/libio/vtables.c
+++ b/libio/vtables.c
@@ -86,11 +86,11 @@
# pragma weak __wprintf_buffer_as_file_overflow
# pragma weak __wprintf_buffer_as_file_xsputn
#endif
-const struct _IO_jump_t __io_vtables[IO_VTABLES_LEN] attribute_relro =
+const struct _IO_jump_t __io_vtables[IO_VTABLES_NUM] attribute_relro =
{
/* _IO_str_jumps */
[IO_STR_JUMPS] =
{
JUMP_INIT_DUMMY,
--
2.41.0
^ permalink raw reply [flat|nested] 5+ messages in thread
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2023-09-08 11:20 ` Florian Weimer
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