[alsa-devel] sound: list corruption in delete_and_unsubscribe_port
Hello,
Here is a new one on 18558cae0272f8fd9647e69d3fec1565a7949865 (4.5-rc4). But need to note that sound become much more stable, I've seen only 2 of these over night.
The following program causes list corruption:
------------[ cut here ]------------ WARNING: CPU: 2 PID: 12546 at lib/list_debug.c:62 __list_del_entry+0x10b/0x1e0() list_del corruption, ffff880063512388->next is LIST_POISON1 (dead000000000100) Modules linked in: CPU: 2 PID: 12546 Comm: a.out Not tainted 4.5.0-rc4+ #328 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 ffffffff87b05080 ffff8800608b7a48 ffffffff82be46cf ffffffff81477fb8 fffffbfff0f60a10 ffff8800608b7ab8 ffff8800637d97c0 ffffffff86ad3780 0000000000000009 000000000000003e ffff8800608b7a88 ffffffff81355139 Call Trace: [<ffffffff81355249>] warn_slowpath_fmt+0xa9/0xd0 kernel/panic.c:494 [<ffffffff82c4c36b>] __list_del_entry+0x10b/0x1e0 lib/list_debug.c:60 [<ffffffff82c4c44d>] list_del+0xd/0x70 lib/list_debug.c:86 [<ffffffff852c38e3>] delete_and_unsubscribe_port+0x1e3/0x2f0 sound/core/seq/seq_ports.c:545 [<ffffffff852c43fa>] clear_subscriber_list+0x15a/0x260 sound/core/seq/seq_ports.c:250 [<ffffffff852c456a>] port_delete+0x6a/0x1c0 sound/core/seq/seq_ports.c:266 [<ffffffff852c5242>] snd_seq_delete_all_ports+0x242/0x350 sound/core/seq/seq_ports.c:330 [<ffffffff852ae1cf>] seq_free_client1+0x2f/0x290 sound/core/seq/seq_clientmgr.c:272 [<ffffffff852ae495>] seq_free_client+0x65/0x160 sound/core/seq/seq_clientmgr.c:299 [<ffffffff852b118d>] snd_seq_release+0x4d/0xb0 sound/core/seq/seq_clientmgr.c:380 [<ffffffff817c3256>] __fput+0x236/0x780 fs/file_table.c:208 [<ffffffff817c3825>] ____fput+0x15/0x20 fs/file_table.c:244 [<ffffffff813b3100>] task_work_run+0x170/0x210 kernel/task_work.c:115 [< inline >] tracehook_notify_resume include/linux/tracehook.h:191 [<ffffffff810066b1>] exit_to_usermode_loop+0x1d1/0x210 arch/x86/entry/common.c:251 [< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:282 [<ffffffff810084ea>] syscall_return_slowpath+0x2ba/0x340 arch/x86/entry/common.c:344 [<ffffffff866626e2>] int_ret_from_sys_call+0x25/0x9f arch/x86/entry/entry_64.S:281 ---[ end trace 4cad985f706f8ace ]--- ------------[ cut here ]------------
// autogenerated by syzkaller (http://github.com/google/syzkaller) #include <pthread.h> #include <stdint.h> #include <string.h> #include <sys/syscall.h> #include <unistd.h>
long r[143];
void* thr(void* arg) { switch ((long)arg) { case 0: syscall(SYS_mmap, 0x20000000ul, 0x40000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul); break; case 1: r[2] = syscall(SYS_open, "/dev/snd/seq", 0x400ul, 0, 0, 0); break; case 2: *(uint8_t*)0x2000df50 = (uint8_t)0xffffffffffffff80; *(uint8_t*)0x2000df51 = (uint8_t)0x1; *(uint8_t*)0x2000df52 = (uint8_t)0xfff; *(uint8_t*)0x2000df53 = (uint8_t)0xb0; *(uint8_t*)0x2000df54 = (uint8_t)0x401; *(uint8_t*)0x2000df55 = (uint8_t)0x7; *(uint8_t*)0x2000df56 = (uint8_t)0x7; *(uint8_t*)0x2000df57 = (uint8_t)0x0; *(uint8_t*)0x2000df58 = (uint8_t)0x1; *(uint8_t*)0x2000df59 = (uint8_t)0x401; *(uint8_t*)0x2000df5a = (uint8_t)0xffffffffffff0001; *(uint8_t*)0x2000df5b = (uint8_t)0x5; *(uint8_t*)0x2000df5c = (uint8_t)0x6; *(uint8_t*)0x2000df5d = (uint8_t)0x0; *(uint8_t*)0x2000df5e = (uint8_t)0xffff; *(uint8_t*)0x2000df5f = (uint8_t)0x3; *(uint8_t*)0x2000df60 = (uint8_t)0x0; *(uint8_t*)0x2000df61 = (uint8_t)0xffffffffffffffc0; *(uint8_t*)0x2000df62 = (uint8_t)0x6; *(uint8_t*)0x2000df63 = (uint8_t)0xfff; *(uint8_t*)0x2000df64 = (uint8_t)0x624c; *(uint8_t*)0x2000df65 = (uint8_t)0x53; *(uint8_t*)0x2000df66 = (uint8_t)0x0; *(uint8_t*)0x2000df67 = (uint8_t)0xfffffffffffffffc; *(uint8_t*)0x2000df68 = (uint8_t)0x3f; *(uint8_t*)0x2000df69 = (uint8_t)0x2; *(uint8_t*)0x2000df6a = (uint8_t)0x4; *(uint8_t*)0x2000df6b = (uint8_t)0x401; *(uint8_t*)0x2000df6c = (uint8_t)0x100000000; *(uint8_t*)0x2000df6d = (uint8_t)0x5; *(uint8_t*)0x2000df6e = (uint8_t)0x1; *(uint8_t*)0x2000df6f = (uint8_t)0x9; *(uint8_t*)0x2000df70 = (uint8_t)0x40; *(uint8_t*)0x2000df71 = (uint8_t)0xfff; *(uint8_t*)0x2000df72 = (uint8_t)0x6; *(uint8_t*)0x2000df73 = (uint8_t)0xffffffffffffff2b; *(uint8_t*)0x2000df74 = (uint8_t)0x1f; *(uint8_t*)0x2000df75 = (uint8_t)0x2; *(uint8_t*)0x2000df76 = (uint8_t)0x4; *(uint8_t*)0x2000df77 = (uint8_t)0x68; *(uint8_t*)0x2000df78 = (uint8_t)0x9c33; *(uint8_t*)0x2000df79 = (uint8_t)0x80; *(uint8_t*)0x2000df7a = (uint8_t)0x3; *(uint8_t*)0x2000df7b = (uint8_t)0x100; *(uint8_t*)0x2000df7c = (uint8_t)0xc1b1; *(uint8_t*)0x2000df7d = (uint8_t)0x3; *(uint8_t*)0x2000df7e = (uint8_t)0x0; *(uint8_t*)0x2000df7f = (uint8_t)0x8; *(uint8_t*)0x2000df80 = (uint8_t)0x3; *(uint8_t*)0x2000df81 = (uint8_t)0x8; *(uint8_t*)0x2000df82 = (uint8_t)0x8; *(uint8_t*)0x2000df83 = (uint8_t)0x5d; *(uint8_t*)0x2000df84 = (uint8_t)0x1; *(uint8_t*)0x2000df85 = (uint8_t)0x9; *(uint8_t*)0x2000df86 = (uint8_t)0x1; *(uint8_t*)0x2000df87 = (uint8_t)0x41; *(uint8_t*)0x2000df88 = (uint8_t)0x3; *(uint8_t*)0x2000df89 = (uint8_t)0x6; *(uint8_t*)0x2000df8a = (uint8_t)0x3f; *(uint8_t*)0x2000df8b = (uint8_t)0x3; *(uint8_t*)0x2000df8c = (uint8_t)0x9; *(uint8_t*)0x2000df8d = (uint8_t)0xffffffffffffff01; *(uint8_t*)0x2000df8e = (uint8_t)0x0; *(uint8_t*)0x2000df8f = (uint8_t)0x6; *(uint8_t*)0x2000df90 = (uint8_t)0xe9c; *(uint8_t*)0x2000df91 = (uint8_t)0x0; *(uint32_t*)0x2000df94 = (uint32_t)0x7b; *(uint32_t*)0x2000df98 = (uint32_t)0x1002; *(uint32_t*)0x2000df9c = (uint32_t)0x9; *(uint32_t*)0x2000dfa0 = (uint32_t)0x1000; *(uint32_t*)0x2000dfa4 = (uint32_t)0x80; *(uint32_t*)0x2000dfa8 = (uint32_t)0x10000; *(uint32_t*)0x2000dfac = (uint32_t)0x8; *(uint64_t*)0x2000dfb0 = (uint64_t)0x0; *(uint32_t*)0x2000dfb8 = (uint32_t)0x3; *(uint32_t*)0x2000dfbc = (uint32_t)0x39; *(uint8_t*)0x2000dfc0 = (uint8_t)0x0; *(uint8_t*)0x2000dfc1 = (uint8_t)0x0; *(uint8_t*)0x2000dfc2 = (uint8_t)0x0; *(uint8_t*)0x2000dfc3 = (uint8_t)0x0; *(uint8_t*)0x2000dfc4 = (uint8_t)0x0; *(uint8_t*)0x2000dfc5 = (uint8_t)0x0; *(uint8_t*)0x2000dfc6 = (uint8_t)0x0; *(uint8_t*)0x2000dfc7 = (uint8_t)0x0; *(uint8_t*)0x2000dfc8 = (uint8_t)0x0; *(uint8_t*)0x2000dfc9 = (uint8_t)0x0; *(uint8_t*)0x2000dfca = (uint8_t)0x0; *(uint8_t*)0x2000dfcb = (uint8_t)0x0; *(uint8_t*)0x2000dfcc = (uint8_t)0x0; *(uint8_t*)0x2000dfcd = (uint8_t)0x0; *(uint8_t*)0x2000dfce = (uint8_t)0x0; *(uint8_t*)0x2000dfcf = (uint8_t)0x0; *(uint8_t*)0x2000dfd0 = (uint8_t)0x0; *(uint8_t*)0x2000dfd1 = (uint8_t)0x0; *(uint8_t*)0x2000dfd2 = (uint8_t)0x0; *(uint8_t*)0x2000dfd3 = (uint8_t)0x0; *(uint8_t*)0x2000dfd4 = (uint8_t)0x0; *(uint8_t*)0x2000dfd5 = (uint8_t)0x0; *(uint8_t*)0x2000dfd6 = (uint8_t)0x0; *(uint8_t*)0x2000dfd7 = (uint8_t)0x0; *(uint8_t*)0x2000dfd8 = (uint8_t)0x0; *(uint8_t*)0x2000dfd9 = (uint8_t)0x0; *(uint8_t*)0x2000dfda = (uint8_t)0x0; *(uint8_t*)0x2000dfdb = (uint8_t)0x0; *(uint8_t*)0x2000dfdc = (uint8_t)0x0; *(uint8_t*)0x2000dfdd = (uint8_t)0x0; *(uint8_t*)0x2000dfde = (uint8_t)0x0; *(uint8_t*)0x2000dfdf = (uint8_t)0x0; *(uint8_t*)0x2000dfe0 = (uint8_t)0x0; *(uint8_t*)0x2000dfe1 = (uint8_t)0x0; *(uint8_t*)0x2000dfe2 = (uint8_t)0x0; *(uint8_t*)0x2000dfe3 = (uint8_t)0x0; *(uint8_t*)0x2000dfe4 = (uint8_t)0x0; *(uint8_t*)0x2000dfe5 = (uint8_t)0x0; *(uint8_t*)0x2000dfe6 = (uint8_t)0x0; *(uint8_t*)0x2000dfe7 = (uint8_t)0x0; *(uint8_t*)0x2000dfe8 = (uint8_t)0x0; *(uint8_t*)0x2000dfe9 = (uint8_t)0x0; *(uint8_t*)0x2000dfea = (uint8_t)0x0; *(uint8_t*)0x2000dfeb = (uint8_t)0x0; *(uint8_t*)0x2000dfec = (uint8_t)0x0; *(uint8_t*)0x2000dfed = (uint8_t)0x0; *(uint8_t*)0x2000dfee = (uint8_t)0x0; *(uint8_t*)0x2000dfef = (uint8_t)0x0; *(uint8_t*)0x2000dff0 = (uint8_t)0x0; *(uint8_t*)0x2000dff1 = (uint8_t)0x0; *(uint8_t*)0x2000dff2 = (uint8_t)0x0; *(uint8_t*)0x2000dff3 = (uint8_t)0x0; *(uint8_t*)0x2000dff4 = (uint8_t)0x0; *(uint8_t*)0x2000dff5 = (uint8_t)0x0; *(uint8_t*)0x2000dff6 = (uint8_t)0x0; *(uint8_t*)0x2000dff7 = (uint8_t)0x0; *(uint8_t*)0x2000dff8 = (uint8_t)0x0; *(uint8_t*)0x2000dff9 = (uint8_t)0x0; *(uint8_t*)0x2000dffa = (uint8_t)0x0; r[138] = syscall(SYS_ioctl, r[2], 0xc0a85320ul, 0x2000df50ul, 0, 0, 0); break; case 3: r[139] = syscall(SYS_read, r[2], 0x20025000ul, 0x75ul, 0, 0, 0); break; case 4: r[140] = syscall(SYS_close, r[2], 0, 0, 0, 0, 0); break; case 5: memcpy((void*)0x20022000, "\x2f\x64\x65\x76\x2f\x73\x65\x71\x75\x65\x6e\x63\x65\x72", 14); syscall(SYS_open, "/dev/sequencer", 0x4000ul, 0, 0, 0); break; } return 0; }
int main() { long i; pthread_t th[6];
srand(getpid()); memset(r, -1, sizeof(r)); for (i = 0; i < 6; i++) { pthread_create(&th[i], 0, thr, (void*)i); usleep(10000); } for (i = 0; i < 6; i++) { pthread_create(&th[i], 0, thr, (void*)i); if (rand() % 2 == 0) usleep(rand() % 10000); } usleep(100000); return 0; }
On Tue, 16 Feb 2016 10:41:54 +0100, Dmitry Vyukov wrote:
Hello,
Here is a new one on 18558cae0272f8fd9647e69d3fec1565a7949865 (4.5-rc4). But need to note that sound become much more stable, I've seen only 2 of these over night.
The following program causes list corruption:
------------[ cut here ]------------ WARNING: CPU: 2 PID: 12546 at lib/list_debug.c:62 __list_del_entry+0x10b/0x1e0() list_del corruption, ffff880063512388->next is LIST_POISON1 (dead000000000100) Modules linked in: CPU: 2 PID: 12546 Comm: a.out Not tainted 4.5.0-rc4+ #328 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 ffffffff87b05080 ffff8800608b7a48 ffffffff82be46cf ffffffff81477fb8 fffffbfff0f60a10 ffff8800608b7ab8 ffff8800637d97c0 ffffffff86ad3780 0000000000000009 000000000000003e ffff8800608b7a88 ffffffff81355139 Call Trace: [<ffffffff81355249>] warn_slowpath_fmt+0xa9/0xd0 kernel/panic.c:494 [<ffffffff82c4c36b>] __list_del_entry+0x10b/0x1e0 lib/list_debug.c:60 [<ffffffff82c4c44d>] list_del+0xd/0x70 lib/list_debug.c:86 [<ffffffff852c38e3>] delete_and_unsubscribe_port+0x1e3/0x2f0 sound/core/seq/seq_ports.c:545 [<ffffffff852c43fa>] clear_subscriber_list+0x15a/0x260 sound/core/seq/seq_ports.c:250 [<ffffffff852c456a>] port_delete+0x6a/0x1c0 sound/core/seq/seq_ports.c:266 [<ffffffff852c5242>] snd_seq_delete_all_ports+0x242/0x350 sound/core/seq/seq_ports.c:330 [<ffffffff852ae1cf>] seq_free_client1+0x2f/0x290 sound/core/seq/seq_clientmgr.c:272 [<ffffffff852ae495>] seq_free_client+0x65/0x160 sound/core/seq/seq_clientmgr.c:299 [<ffffffff852b118d>] snd_seq_release+0x4d/0xb0 sound/core/seq/seq_clientmgr.c:380 [<ffffffff817c3256>] __fput+0x236/0x780 fs/file_table.c:208 [<ffffffff817c3825>] ____fput+0x15/0x20 fs/file_table.c:244 [<ffffffff813b3100>] task_work_run+0x170/0x210 kernel/task_work.c:115 [< inline >] tracehook_notify_resume include/linux/tracehook.h:191 [<ffffffff810066b1>] exit_to_usermode_loop+0x1d1/0x210 arch/x86/entry/common.c:251 [< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:282 [<ffffffff810084ea>] syscall_return_slowpath+0x2ba/0x340 arch/x86/entry/common.c:344 [<ffffffff866626e2>] int_ret_from_sys_call+0x25/0x9f arch/x86/entry/entry_64.S:281 ---[ end trace 4cad985f706f8ace ]---
Hm, this might be the remaining open race at deleting ports. Please try the patch below.
thanks,
Takashi
--- diff --git a/sound/core/seq/seq_ports.c b/sound/core/seq/seq_ports.c index 921fb2bd8fad..fe686ee41c6d 100644 --- a/sound/core/seq/seq_ports.c +++ b/sound/core/seq/seq_ports.c @@ -535,19 +535,22 @@ static void delete_and_unsubscribe_port(struct snd_seq_client *client, bool is_src, bool ack) { struct snd_seq_port_subs_info *grp; + struct list_head *list; + bool empty;
grp = is_src ? &port->c_src : &port->c_dest; + list = is_src ? &subs->src_list : &subs->dest_list; down_write(&grp->list_mutex); write_lock_irq(&grp->list_lock); - if (is_src) - list_del(&subs->src_list); - else - list_del(&subs->dest_list); + empty = list_empty(list); + if (!empty) + list_del_init(list); grp->exclusive = 0; write_unlock_irq(&grp->list_lock); up_write(&grp->list_mutex);
- unsubscribe_port(client, port, grp, &subs->info, ack); + if (!empty) + unsubscribe_port(client, port, grp, &subs->info, ack); }
/* connect two ports */
On Tue, Feb 16, 2016 at 11:00 AM, Takashi Iwai tiwai@suse.de wrote:
On Tue, 16 Feb 2016 10:41:54 +0100, Dmitry Vyukov wrote:
Hello,
Here is a new one on 18558cae0272f8fd9647e69d3fec1565a7949865 (4.5-rc4). But need to note that sound become much more stable, I've seen only 2 of these over night.
The following program causes list corruption:
------------[ cut here ]------------ WARNING: CPU: 2 PID: 12546 at lib/list_debug.c:62 __list_del_entry+0x10b/0x1e0() list_del corruption, ffff880063512388->next is LIST_POISON1 (dead000000000100) Modules linked in: CPU: 2 PID: 12546 Comm: a.out Not tainted 4.5.0-rc4+ #328 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 ffffffff87b05080 ffff8800608b7a48 ffffffff82be46cf ffffffff81477fb8 fffffbfff0f60a10 ffff8800608b7ab8 ffff8800637d97c0 ffffffff86ad3780 0000000000000009 000000000000003e ffff8800608b7a88 ffffffff81355139 Call Trace: [<ffffffff81355249>] warn_slowpath_fmt+0xa9/0xd0 kernel/panic.c:494 [<ffffffff82c4c36b>] __list_del_entry+0x10b/0x1e0 lib/list_debug.c:60 [<ffffffff82c4c44d>] list_del+0xd/0x70 lib/list_debug.c:86 [<ffffffff852c38e3>] delete_and_unsubscribe_port+0x1e3/0x2f0 sound/core/seq/seq_ports.c:545 [<ffffffff852c43fa>] clear_subscriber_list+0x15a/0x260 sound/core/seq/seq_ports.c:250 [<ffffffff852c456a>] port_delete+0x6a/0x1c0 sound/core/seq/seq_ports.c:266 [<ffffffff852c5242>] snd_seq_delete_all_ports+0x242/0x350 sound/core/seq/seq_ports.c:330 [<ffffffff852ae1cf>] seq_free_client1+0x2f/0x290 sound/core/seq/seq_clientmgr.c:272 [<ffffffff852ae495>] seq_free_client+0x65/0x160 sound/core/seq/seq_clientmgr.c:299 [<ffffffff852b118d>] snd_seq_release+0x4d/0xb0 sound/core/seq/seq_clientmgr.c:380 [<ffffffff817c3256>] __fput+0x236/0x780 fs/file_table.c:208 [<ffffffff817c3825>] ____fput+0x15/0x20 fs/file_table.c:244 [<ffffffff813b3100>] task_work_run+0x170/0x210 kernel/task_work.c:115 [< inline >] tracehook_notify_resume include/linux/tracehook.h:191 [<ffffffff810066b1>] exit_to_usermode_loop+0x1d1/0x210 arch/x86/entry/common.c:251 [< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:282 [<ffffffff810084ea>] syscall_return_slowpath+0x2ba/0x340 arch/x86/entry/common.c:344 [<ffffffff866626e2>] int_ret_from_sys_call+0x25/0x9f arch/x86/entry/entry_64.S:281 ---[ end trace 4cad985f706f8ace ]---
Hm, this might be the remaining open race at deleting ports. Please try the patch below.
Yes, it fixes the crash for me.
Tested-by: Dmitry Vyukov dvyukov@google.com
Thanks!
thanks,
Takashi
diff --git a/sound/core/seq/seq_ports.c b/sound/core/seq/seq_ports.c index 921fb2bd8fad..fe686ee41c6d 100644 --- a/sound/core/seq/seq_ports.c +++ b/sound/core/seq/seq_ports.c @@ -535,19 +535,22 @@ static void delete_and_unsubscribe_port(struct snd_seq_client *client, bool is_src, bool ack) { struct snd_seq_port_subs_info *grp;
struct list_head *list;bool empty; grp = is_src ? &port->c_src : &port->c_dest;list = is_src ? &subs->src_list : &subs->dest_list; down_write(&grp->list_mutex); write_lock_irq(&grp->list_lock);
if (is_src)list_del(&subs->src_list);elselist_del(&subs->dest_list);
empty = list_empty(list);if (!empty)list_del_init(list); grp->exclusive = 0; write_unlock_irq(&grp->list_lock); up_write(&grp->list_mutex);
unsubscribe_port(client, port, grp, &subs->info, ack);
if (!empty)unsubscribe_port(client, port, grp, &subs->info, ack);}
/* connect two ports */
On Tue, 16 Feb 2016 12:19:31 +0100, Dmitry Vyukov wrote:
On Tue, Feb 16, 2016 at 11:00 AM, Takashi Iwai tiwai@suse.de wrote:
On Tue, 16 Feb 2016 10:41:54 +0100, Dmitry Vyukov wrote:
Hello,
Here is a new one on 18558cae0272f8fd9647e69d3fec1565a7949865 (4.5-rc4). But need to note that sound become much more stable, I've seen only 2 of these over night.
The following program causes list corruption:
------------[ cut here ]------------ WARNING: CPU: 2 PID: 12546 at lib/list_debug.c:62 __list_del_entry+0x10b/0x1e0() list_del corruption, ffff880063512388->next is LIST_POISON1 (dead000000000100) Modules linked in: CPU: 2 PID: 12546 Comm: a.out Not tainted 4.5.0-rc4+ #328 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 ffffffff87b05080 ffff8800608b7a48 ffffffff82be46cf ffffffff81477fb8 fffffbfff0f60a10 ffff8800608b7ab8 ffff8800637d97c0 ffffffff86ad3780 0000000000000009 000000000000003e ffff8800608b7a88 ffffffff81355139 Call Trace: [<ffffffff81355249>] warn_slowpath_fmt+0xa9/0xd0 kernel/panic.c:494 [<ffffffff82c4c36b>] __list_del_entry+0x10b/0x1e0 lib/list_debug.c:60 [<ffffffff82c4c44d>] list_del+0xd/0x70 lib/list_debug.c:86 [<ffffffff852c38e3>] delete_and_unsubscribe_port+0x1e3/0x2f0 sound/core/seq/seq_ports.c:545 [<ffffffff852c43fa>] clear_subscriber_list+0x15a/0x260 sound/core/seq/seq_ports.c:250 [<ffffffff852c456a>] port_delete+0x6a/0x1c0 sound/core/seq/seq_ports.c:266 [<ffffffff852c5242>] snd_seq_delete_all_ports+0x242/0x350 sound/core/seq/seq_ports.c:330 [<ffffffff852ae1cf>] seq_free_client1+0x2f/0x290 sound/core/seq/seq_clientmgr.c:272 [<ffffffff852ae495>] seq_free_client+0x65/0x160 sound/core/seq/seq_clientmgr.c:299 [<ffffffff852b118d>] snd_seq_release+0x4d/0xb0 sound/core/seq/seq_clientmgr.c:380 [<ffffffff817c3256>] __fput+0x236/0x780 fs/file_table.c:208 [<ffffffff817c3825>] ____fput+0x15/0x20 fs/file_table.c:244 [<ffffffff813b3100>] task_work_run+0x170/0x210 kernel/task_work.c:115 [< inline >] tracehook_notify_resume include/linux/tracehook.h:191 [<ffffffff810066b1>] exit_to_usermode_loop+0x1d1/0x210 arch/x86/entry/common.c:251 [< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:282 [<ffffffff810084ea>] syscall_return_slowpath+0x2ba/0x340 arch/x86/entry/common.c:344 [<ffffffff866626e2>] int_ret_from_sys_call+0x25/0x9f arch/x86/entry/entry_64.S:281 ---[ end trace 4cad985f706f8ace ]---
Hm, this might be the remaining open race at deleting ports. Please try the patch below.
Yes, it fixes the crash for me.
Tested-by: Dmitry Vyukov dvyukov@google.com
Thanks!
Good to hear. FWIW, below is the final patch I'm going to queue. Thanks for quick testing!
Takashi
-- 8< -- From: Takashi Iwai tiwai@suse.de Subject: [PATCH] ALSA: seq: Fix double port list deletion
The commit [7f0973e973cd: ALSA: seq: Fix lockdep warnings due to double mutex locks] split the management of two linked lists (source and destination) into two individual calls for avoiding the AB/BA deadlock. However, this may leave the possible double deletion of one of two lists when the counterpart is being deleted concurrently. It ends up with a list corruption, as revealed by syzkaller fuzzer.
This patch fixes it by checking the list emptiness and skipping the deletion and the following process.
BugLink: http://lkml.kernel.org/r/CACT4Y+bay9qsrz6dQu31EcGaH9XwfW7o3oBzSQUG9fMszoh=Sg... Fixes: 7f0973e973cd ('ALSA: seq: Fix lockdep warnings due to 'double mutex locks) Reported-by: Dmitry Vyukov dvyukov@google.com Tested-by: Dmitry Vyukov dvyukov@google.com Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/core/seq/seq_ports.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/sound/core/seq/seq_ports.c b/sound/core/seq/seq_ports.c index 921fb2bd8fad..fe686ee41c6d 100644 --- a/sound/core/seq/seq_ports.c +++ b/sound/core/seq/seq_ports.c @@ -535,19 +535,22 @@ static void delete_and_unsubscribe_port(struct snd_seq_client *client, bool is_src, bool ack) { struct snd_seq_port_subs_info *grp; + struct list_head *list; + bool empty;
grp = is_src ? &port->c_src : &port->c_dest; + list = is_src ? &subs->src_list : &subs->dest_list; down_write(&grp->list_mutex); write_lock_irq(&grp->list_lock); - if (is_src) - list_del(&subs->src_list); - else - list_del(&subs->dest_list); + empty = list_empty(list); + if (!empty) + list_del_init(list); grp->exclusive = 0; write_unlock_irq(&grp->list_lock); up_write(&grp->list_mutex);
- unsubscribe_port(client, port, grp, &subs->info, ack); + if (!empty) + unsubscribe_port(client, port, grp, &subs->info, ack); }
/* connect two ports */
participants (2)
-
Dmitry Vyukov -
Takashi Iwai