From: Rich Felker <dalias@libc.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: musl@lists.openwall.com, Takashi Iwai <tiwai@suse.de>,
Michael Forney <mforney@mforney.org>,
ALSA Development Mailing List <alsa-devel@alsa-project.org>,
Takashi Iwai <tiwai@suse.com>,
Baolin Wang <baolin.wang@linaro.org>,
y2038 Mailman List <y2038@lists.linaro.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Mark Brown <broonie@kernel.org>,
Baolin Wang <baolin.wang7@gmail.com>
Subject: Re: [musl] Re: [alsa-devel] [PATCH v7 8/9] ALSA: add new 32-bit layout for snd_pcm_mmap_status/control
Date: Tue, 19 Oct 2021 10:16:24 -0400 [thread overview]
Message-ID: <20211019141622.GN7074@brightrain.aerifal.cx> (raw)
In-Reply-To: <20211018204203.GM7074@brightrain.aerifal.cx>
[-- Attachment #1: Type: text/plain, Size: 1704 bytes --]
On Mon, Oct 18, 2021 at 04:42:04PM -0400, Rich Felker wrote:
> On Mon, Oct 18, 2021 at 05:26:35PM +0200, Arnd Bergmann wrote:
> > On Mon, Oct 18, 2021 at 5:08 PM Rich Felker <dalias@libc.org> wrote:
> > > On Mon, Oct 18, 2021 at 04:58:03PM +0200, Takashi Iwai wrote:
> > > > On Mon, 18 Oct 2021 16:43:00 +0200, Rich Felker wrote:
> > >
> > > No, I don't think so. The musl translator is to translate between the
> > > time64 ioctl structures and the old time32 ones for the sake of
> > > executing on an old kernel. Up til now, it has been broken comparably
> > > to how 32-bit binaries running in compat mode on a 64-bit kernel were
> > > broken: the code in musl translated the time64 structure to (and back
> > > from) the time32 one assuming the intended padding. But the
> > > application was using the actual kernel uapi struct where the padding
> > > was (and still is) illogical. Thus, nothing was built with the wrong
> > > ABI; it's only the musl-internal translation logic that was wrong (and
> > > only pre-time64 kernels are affected).
> > >
> > > The attached patch should fix it, I think.
> > >
> > > + int adj = BYTE_ORDER==BIG_ENDIAN ? 4 : 0;
> > > + if (dir==W) {
> > > + memcpy(old+68, new+72+adj, 4);
> > > + memcpy(old+72, new+72+4+2*adj, 4);
> >
> > I think that should be "new+72+4+3*adj": the "2*adj" would
> > be what the code does already for the originally intended
> > format.
>
> Well for little endian either would work (because adj is 0 :) but yes
> there are 3 such paddings before the second member on big endian, so
> it should be 3.
How about this? It avoids open coding the logic and handles it as 2
4-byte substructures with endian-specific offsets.
Rich
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diff --git a/src/misc/ioctl.c b/src/misc/ioctl.c
index 49282811..35804f02 100644
--- a/src/misc/ioctl.c
+++ b/src/misc/ioctl.c
@@ -6,6 +6,7 @@
#include <stddef.h>
#include <stdint.h>
#include <string.h>
+#include <endian.h>
#include "syscall.h"
#define alignof(t) offsetof(struct { char c; t x; }, x)
@@ -53,7 +54,7 @@ static const struct ioctl_compat_map compat_map[] = {
{ _IOWR('A', 0x23, char[136]), _IOWR('A', 0x23, char[132]), 0, WR, 1, 0 },
{ 0, 0, 4, WR, 1, 0 }, /* snd_pcm_sync_ptr (flags only) */
{ 0, 0, 32, WR, 1, OFFS(8,12,16,24,28) }, /* snd_pcm_mmap_status */
- { 0, 0, 8, WR, 1, OFFS(0,4) }, /* snd_pcm_mmap_control */
+ { 0, 0, 4, WR, 1, 0 }, /* snd_pcm_mmap_control (each member) */
/* VIDIOC_QUERYBUF, VIDIOC_QBUF, VIDIOC_DQBUF, VIDIOC_PREPARE_BUF */
{ _IOWR('V', 9, new_misaligned(68)), _IOWR('V', 9, char[68]), 68, WR, 1, OFFS(20, 24) },
@@ -90,7 +91,11 @@ static void convert_ioctl_struct(const struct ioctl_compat_map *map, char *old,
* if another exception appears this needs changing. */
convert_ioctl_struct(map+1, old, new, dir);
convert_ioctl_struct(map+2, old+4, new+8, dir);
- convert_ioctl_struct(map+3, old+68, new+72, dir);
+ /* snd_pcm_mmap_control, special-cased due to kernel
+ * type definition having been botched. */
+ int adj = BYTE_ORDER==BIG_ENDIAN ? 4 : 0;
+ convert_ioctl_struct(map+3, old+68, new+72+adj, dir);
+ convert_ioctl_struct(map+3, old+72, new+76+3*adj, dir);
return;
}
for (int i=0; i < map->noffs; i++) {
next prev parent reply other threads:[~2021-10-19 14:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20191211212025.1981822-1-arnd@arndb.de>
[not found] ` <20191211212025.1981822-9-arnd@arndb.de>
[not found] ` <29QBMJU8DE71E.2YZSH8IHT5HMH@mforney.org>
[not found] ` <s5hpmsh9kdx.wl-tiwai@suse.de>
[not found] ` <CAK8P3a0K3XtjiszC3XWgG0L8+AgO+xUGr_KEAnb9a5GmyecoUQ@mail.gmail.com>
[not found] ` <s5hee8x9f92.wl-tiwai@suse.de>
2021-10-07 13:11 ` Arnd Bergmann
2021-10-07 15:33 ` Takashi Iwai
2021-10-07 16:06 ` Rich Felker
2021-10-07 16:18 ` Takashi Iwai
2021-10-07 16:51 ` Rich Felker
2021-10-08 8:43 ` Takashi Iwai
2021-10-08 8:44 ` Takashi Iwai
2021-10-08 9:24 ` Arnd Bergmann
2021-10-08 11:11 ` Takashi Iwai
2021-10-08 11:45 ` Arnd Bergmann
2021-10-08 11:53 ` Takashi Iwai
2021-10-08 12:13 ` Arnd Bergmann
2021-10-08 12:07 ` Rich Felker
2021-10-10 7:53 ` Takashi Iwai
2021-10-18 14:43 ` Rich Felker
2021-10-18 14:58 ` Takashi Iwai
2021-10-18 15:08 ` Rich Felker
2021-10-18 15:26 ` Arnd Bergmann
2021-10-18 20:42 ` Rich Felker
2021-10-19 14:16 ` Rich Felker [this message]
2021-10-19 14:23 ` Arnd Bergmann
2021-10-08 12:06 ` Rich Felker
2021-10-08 12:37 ` Arnd Bergmann
2021-10-08 17:20 ` Rich Felker
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