On Fri, Nov 9, 2018 at 12:18 PM Takashi Iwai <tiwai@xxxxxxx> wrote: > > On Fri, 09 Nov 2018 10:31:03 +0100, > Alexander Potapenko wrote: > > > > On Thu, Nov 8, 2018 at 9:38 PM syzbot > > <syzbot+1cb36954e127c98dd037@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > Hello, > > > > > > syzbot found the following crash on: > > > > > > HEAD commit: 7438a3b20295 kmsan: print user address when reporting info.. > > > git tree: https://github.com/google/kmsan.git/master > > > console output: https://syzkaller.appspot.com/x/log.txt?x=15b42133400000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=8df5fc509a1b351b > > > dashboard link: https://syzkaller.appspot.com/bug?extid=1cb36954e127c98dd037 > > > compiler: clang version 8.0.0 (trunk 343298) > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12be9825400000 > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13e2c425400000 > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > > Reported-by: syzbot+1cb36954e127c98dd037@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > > ================================================================== > > > BUG: KMSAN: uninit-value in __arch_swab32 > > > arch/x86/include/uapi/asm/swab.h:10 [inline] > > > BUG: KMSAN: uninit-value in __fswab32 include/uapi/linux/swab.h:59 [inline] > > > BUG: KMSAN: uninit-value in do_convert sound/core/oss/linear.c:50 [inline] > > > BUG: KMSAN: uninit-value in convert sound/core/oss/linear.c:81 [inline] > > > BUG: KMSAN: uninit-value in linear_transfer+0x92d/0xca0 > > > sound/core/oss/linear.c:110 > > > CPU: 1 PID: 6835 Comm: syz-executor866 Not tainted 4.19.0+ #78 > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > > Google 01/01/2011 > > > Call Trace: > > > __dump_stack lib/dump_stack.c:77 [inline] > > > dump_stack+0x32d/0x480 lib/dump_stack.c:113 > > > kmsan_report+0x19f/0x300 mm/kmsan/kmsan.c:911 > > > __msan_warning+0x76/0xd0 mm/kmsan/kmsan_instr.c:415 > > > __arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline] > > > __fswab32 include/uapi/linux/swab.h:59 [inline] > > > do_convert sound/core/oss/linear.c:50 [inline] > > > convert sound/core/oss/linear.c:81 [inline] > > > linear_transfer+0x92d/0xca0 sound/core/oss/linear.c:110 > > > snd_pcm_plug_read_transfer+0x3bf/0x590 sound/core/oss/pcm_plugin.c:659 > > > snd_pcm_oss_read2 sound/core/oss/pcm_oss.c:1480 [inline] > > > snd_pcm_oss_read1 sound/core/oss/pcm_oss.c:1518 [inline] > > > snd_pcm_oss_read+0xe6d/0x1cb0 sound/core/oss/pcm_oss.c:2758 > > > __vfs_read+0x1e2/0xb10 fs/read_write.c:416 > > > vfs_read+0x380/0x6b0 fs/read_write.c:452 > > > ksys_read fs/read_write.c:578 [inline] > > > __do_sys_read fs/read_write.c:588 [inline] > > > __se_sys_read+0x17a/0x370 fs/read_write.c:586 > > > __x64_sys_read+0x4a/0x70 fs/read_write.c:586 > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291 > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7 > > > RIP: 0033:0x446379 > > > Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 > > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff > > > ff 0f 83 7b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 > > > RSP: 002b:00007fcd5b97cda8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 > > > RAX: ffffffffffffffda RBX: 00000000006dac38 RCX: 0000000000446379 > > > RDX: 0000000000000184 RSI: 0000000020002180 RDI: 0000000000000003 > > > RBP: 00000000006dac30 R08: 0000000000000000 R09: 0000000000000000 > > > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac3c > > > R13: 7073642f7665642f R14: 00800000c0045002 R15: 0000000000000001 > > > > > > Uninit was stored to memory at: > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:252 [inline] > > > kmsan_save_stack mm/kmsan/kmsan.c:267 [inline] > > > kmsan_internal_chain_origin+0x136/0x240 mm/kmsan/kmsan.c:569 > > > kmsan_memcpy_origins+0x13d/0x1b0 mm/kmsan/kmsan.c:393 > > > __msan_memcpy+0x6f/0x80 mm/kmsan/kmsan_instr.c:242 > > > do_convert sound/core/oss/linear.c:48 [inline] > > > convert sound/core/oss/linear.c:81 [inline] > > > linear_transfer+0x74c/0xca0 sound/core/oss/linear.c:110 > > > snd_pcm_plug_read_transfer+0x3bf/0x590 sound/core/oss/pcm_plugin.c:659 > > > snd_pcm_oss_read2 sound/core/oss/pcm_oss.c:1480 [inline] > > > snd_pcm_oss_read1 sound/core/oss/pcm_oss.c:1518 [inline] > > > snd_pcm_oss_read+0xe6d/0x1cb0 sound/core/oss/pcm_oss.c:2758 > > > __vfs_read+0x1e2/0xb10 fs/read_write.c:416 > > > vfs_read+0x380/0x6b0 fs/read_write.c:452 > > > ksys_read fs/read_write.c:578 [inline] > > > __do_sys_read fs/read_write.c:588 [inline] > > > __se_sys_read+0x17a/0x370 fs/read_write.c:586 > > > __x64_sys_read+0x4a/0x70 fs/read_write.c:586 > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291 > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7 > > > > > > Uninit was created at: > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:252 [inline] > > > kmsan_internal_alloc_meta_for_pages+0x155/0x740 mm/kmsan/kmsan.c:689 > > > kmsan_alloc_page+0x77/0xe0 mm/kmsan/kmsan_hooks.c:320 > > > __alloc_pages_nodemask+0x12cc/0x6640 mm/page_alloc.c:4416 > > > alloc_pages_current+0x584/0x7e0 mm/mempolicy.c:2093 > > > alloc_pages include/linux/gfp.h:511 [inline] > > > __vmalloc_area_node mm/vmalloc.c:1689 [inline] > > > __vmalloc_node_range+0x879/0x12a0 mm/vmalloc.c:1752 > > > __vmalloc_node mm/vmalloc.c:1797 [inline] > > > __vmalloc_node_flags mm/vmalloc.c:1811 [inline] > > > vmalloc+0xd8/0xf0 mm/vmalloc.c:1833 > > > snd_pcm_plugin_alloc+0x255/0xc80 sound/core/oss/pcm_plugin.c:71 > > > snd_pcm_plug_alloc+0x281/0x600 sound/core/oss/pcm_plugin.c:137 > > > snd_pcm_oss_change_params_locked+0x5e40/0x6e30 > > > sound/core/oss/pcm_oss.c:1039 > > > snd_pcm_oss_change_params sound/core/oss/pcm_oss.c:1107 [inline] > > > snd_pcm_oss_get_active_substream+0x4f7/0x5a0 sound/core/oss/pcm_oss.c:1124 > > > snd_pcm_oss_get_rate sound/core/oss/pcm_oss.c:1774 [inline] > > > snd_pcm_oss_set_rate sound/core/oss/pcm_oss.c:1766 [inline] > > > snd_pcm_oss_ioctl+0x4adb/0x8860 sound/core/oss/pcm_oss.c:2614 > > > do_vfs_ioctl+0xf77/0x2d30 fs/ioctl.c:46 > > > ksys_ioctl fs/ioctl.c:702 [inline] > > > __do_sys_ioctl fs/ioctl.c:709 [inline] > > > __se_sys_ioctl+0x1da/0x270 fs/ioctl.c:707 > > > __x64_sys_ioctl+0x4a/0x70 fs/ioctl.c:707 > > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291 > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7 > > > ================================================================== > > > > I am actually unsure whether this is a true positive or not. > > snd_pcm_plugin_alloc() allocates plugin->buf using vmalloc(size) (see > > https://elixir.bootlin.com/linux/v4.20-rc1/source/sound/core/oss/pcm_plugin.c#L70) > > KMSAN doesn't know where this buffer is initialized (any help finding > > this out is welcome!), so we mark |size| bytes starting from > > plugin->buf as initialized: > > https://github.com/google/kmsan/blob/master/sound/core/oss/pcm_plugin.c#L78 > > But when |size| is not page-aligned vmalloc() still allocates whole > > page, and in the report above linear_transfer() appears to run past > > |size| bytes and read the tail bytes. > > KASAN doesn't detect this bug, because it doesn't handle vmalloc'ed > > (and these bytes are addressable anyway). > > It's still strange that the conversion function gets called for the > uninitialized source. But we should clear the vmalloc page in anyway > for avoiding such a problem. And even better would be to use > kvzalloc() for a better performance. > > Could you check whether the patch works? The patch works and fixes the problem for me. > I forgot the way to trigger the test for kmsan stuff. IIRC, just > pushing to my tree and triggering syz test won't work for KMSAN, > right? Right, you need to test against KMSAN tree, see https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs > > thanks, > > Takashi > > -- 8< -- > From: Takashi Iwai <tiwai@xxxxxxx> > Subject: [PATCH] ALSA: oss: Use kvzalloc() for local buffer allocations > > PCM OSS layer may allocate a few temporary buffers, one for the core > read/write and another for the conversions via plugins. Currently > both are allocated via vmalloc(). But as the allocation size is > equivalent with the PCM period size, the required size might be quite > small, depending on the application. > > This patch replaces these vmalloc() calls with kvzalloc() for covering > small period sizes better. Also, we use "z"-alloc variant here for > addressing the possible uninitialized access reported by syzkaller. > > [ More reported-by and tested-by here in the final version ] > > Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> > --- > sound/core/oss/pcm_oss.c | 6 +++--- > sound/core/oss/pcm_plugin.c | 6 +++--- > 2 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c > index f8d4a419f3af..467039b342b5 100644 > --- a/sound/core/oss/pcm_oss.c > +++ b/sound/core/oss/pcm_oss.c > @@ -1062,8 +1062,8 @@ static int snd_pcm_oss_change_params_locked(struct snd_pcm_substream *substream) > runtime->oss.channels = params_channels(params); > runtime->oss.rate = params_rate(params); > > - vfree(runtime->oss.buffer); > - runtime->oss.buffer = vmalloc(runtime->oss.period_bytes); > + kvfree(runtime->oss.buffer); > + runtime->oss.buffer = kvzalloc(runtime->oss.period_bytes, GFP_KERNEL); > if (!runtime->oss.buffer) { > err = -ENOMEM; > goto failure; > @@ -2328,7 +2328,7 @@ static void snd_pcm_oss_release_substream(struct snd_pcm_substream *substream) > { > struct snd_pcm_runtime *runtime; > runtime = substream->runtime; > - vfree(runtime->oss.buffer); > + kvfree(runtime->oss.buffer); > runtime->oss.buffer = NULL; > #ifdef CONFIG_SND_PCM_OSS_PLUGINS > snd_pcm_oss_plugin_clear(substream); > diff --git a/sound/core/oss/pcm_plugin.c b/sound/core/oss/pcm_plugin.c > index 141c5f3a9575..31cb2acf8afc 100644 > --- a/sound/core/oss/pcm_plugin.c > +++ b/sound/core/oss/pcm_plugin.c > @@ -66,8 +66,8 @@ static int snd_pcm_plugin_alloc(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t > return -ENXIO; > size /= 8; > if (plugin->buf_frames < frames) { > - vfree(plugin->buf); > - plugin->buf = vmalloc(size); > + kvfree(plugin->buf); > + plugin->buf = kvzalloc(size, GFP_KERNEL); > plugin->buf_frames = frames; > } > if (!plugin->buf) { > @@ -191,7 +191,7 @@ int snd_pcm_plugin_free(struct snd_pcm_plugin *plugin) > if (plugin->private_free) > plugin->private_free(plugin); > kfree(plugin->buf_channels); > - vfree(plugin->buf); > + kvfree(plugin->buf); > kfree(plugin); > return 0; > } > -- > 2.19.1 > -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Straße, 33 80636 München Geschäftsführer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
