INFO: task syz-executor can't die for more than 143 seconds.

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syzbot

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Jun 12, 2019, 4:53:07 PM6/12/19
to linux-...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, vi...@zeniv.linux.org.uk
Hello,

syzbot found the following crash on:

HEAD commit: 81a72c79 Add linux-next specific files for 20190612
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1451d31ea00000
kernel config: https://syzkaller.appspot.com/x/.config?x=8aa46bbce201b8b6
dashboard link: https://syzkaller.appspot.com/bug?extid=8ab2d0f39fb79fe6ca40
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1250ae3ea00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1568557aa00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+8ab2d0...@syzkaller.appspotmail.com

INFO: task syz-executor050:8619 can't die for more than 143 seconds.
syz-executor050 R running task 27536 8619 8618 0x00004006
Call Trace:

Showing all locks held in the system:
1 lock held by khungtaskd/1046:
#0: 00000000f58b83ec (rcu_read_lock){....}, at:
debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5262
1 lock held by rsyslogd/8504:
#0: 00000000b8867a10 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110
fs/file.c:801
2 locks held by getty/8594:
#0: 000000008c94b07f (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
#1: 000000006c5169d5 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8595:
#0: 0000000042bd87ed (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
#1: 000000009ebc0e1a (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8596:
#0: 00000000ad647db4 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
#1: 00000000f68a3152 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8597:
#0: 0000000072ec45a9 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
#1: 00000000daa58f5f (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8598:
#0: 000000007698feb5 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
#1: 0000000017a6b41f (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8599:
#0: 00000000f5a5df8a (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
#1: 000000003ed47aa1 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
2 locks held by getty/8600:
#0: 00000000ab9f490c (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341
#1: 00000000332ddba5 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156
1 lock held by syz-executor050/8619:

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 1046 Comm: khungtaskd Not tainted 5.2.0-rc4-next-20190612 #13
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+0x172/0x1f0 lib/dump_stack.c:113
nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1be/0x236 lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:249 [inline]
watchdog+0xb88/0x12b0 kernel/hung_task.c:333
kthread+0x354/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8619 Comm: syz-executor050 Not tainted 5.2.0-rc4-next-20190612
#13
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x50 kernel/kcov.c:101
Code: f4 ff ff ff e8 9d fa e9 ff 48 c7 05 ce b0 15 09 00 00 00 00 e9 a4 e9
ff ff 90 90 90 90 90 90 90 90 90 55 48 89 e5 48 8b 75 08 <65> 48 8b 04 25
c0 fd 01 00 65 8b 15 f0 fa 90 7e 81 e2 00 01 1f 00
RSP: 0018:ffff8880a9acfd80 EFLAGS: 00000206
RAX: 1ffffd40000720d9 RBX: 0000160000000000 RCX: ffffffff81682654
RDX: 0000000000000000 RSI: ffffffff8168263c RDI: ffffea00003906c8
RBP: ffff8880a9acfd80 R08: ffff88808fe146c0 R09: 0000000000000002
R10: ffff88808fe14f78 R11: ffff88808fe146c0 R12: ffffea0000390688
R13: dffffc0000000000 R14: ffffea0000390680 R15: 00000000049a5000
FS: 0000555555a3e880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 00000000a3d59000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
page_to_boot_pfn include/linux/kexec.h:325 [inline]
kimage_alloc_page+0xac/0x9f0 kernel/kexec_core.c:708
kimage_load_normal_segment kernel/kexec_core.c:802 [inline]
kimage_load_segment+0x25d/0x740 kernel/kexec_core.c:919
do_kexec_load+0x41a/0x600 kernel/kexec.c:157
__do_sys_kexec_load kernel/kexec.c:251 [inline]
__se_sys_kexec_load kernel/kexec.c:226 [inline]
__x64_sys_kexec_load+0x1d5/0x260 kernel/kexec.c:226
do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441149
Code: e8 fc ab 02 00 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 9b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd407ca1e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000f6
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441149
RDX: 0000000020000100 RSI: 0000000000000001 RDI: fffffffffffffffe
RBP: 00000000006cb018 R08: 0000000000000004 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401f70
R13: 0000000000402000 R14: 0000000000000000 R15: 0000000000000000


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

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https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

syzbot

unread,
Jun 12, 2019, 10:53:00 PM6/12/19
to jae...@kernel.org, linux-f2...@lists.sourceforge.net, linux-...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, vi...@zeniv.linux.org.uk, yuc...@huawei.com
syzbot has bisected this bug to:

commit 4ddc1b28aac57a90c6426d55e0dea3c1b5eb4782
Author: Chao Yu <yuc...@huawei.com>
Date: Wed Jul 25 23:19:48 2018 +0000

f2fs: fix to restrict mount condition when without CONFIG_QUOTA

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=142f4e49a00000
start commit: 81a72c79 Add linux-next specific files for 20190612
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=122f4e49a00000
Reported-by: syzbot+8ab2d0...@syzkaller.appspotmail.com
Fixes: 4ddc1b28aac5 ("f2fs: fix to restrict mount condition when without
CONFIG_QUOTA")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Tetsuo Handa

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Jun 14, 2019, 6:17:33 AM6/14/19
to Eric Biederman, syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com
syzbot found that a thread can stall for minutes inside kexec_load() after
that thread was killed by SIGKILL [1]. It turned out that the reproducer
was trying to allocate 2408MB of memory using kimage_alloc_page() from
kimage_load_normal_segment(). Let's check for SIGKILL before doing memory
allocation.

[1] https://syzkaller.appspot.com/bug?id=a0e3436829698d5824231251fad9d8e998f94f5e

Signed-off-by: Tetsuo Handa <penguin...@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+8ab2d0...@syzkaller.appspotmail.com>
---
kernel/kexec_core.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index fd5c95f..2b25d95 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -302,6 +302,8 @@ static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order)
{
struct page *pages;

+ if (fatal_signal_pending(current))
+ return NULL;
pages = alloc_pages(gfp_mask & ~__GFP_ZERO, order);
if (pages) {
unsigned int count, i;
--
1.8.3.1

Tetsuo Handa

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Jun 21, 2019, 5:58:57 AM6/21/19
to Laura Abbott, Sumit Semwal, syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello.

I noticed (using below debug patch and reproducer) that memory allocation from
ion_system_heap_allocate() is calling ion_system_heap_shrink(). Is such behavior
what we want?

----------------------------------------
diff --git a/drivers/staging/android/ion/ion.h b/drivers/staging/android/ion/ion.h
index e291299fd35f..ce096d520915 100644
--- a/drivers/staging/android/ion/ion.h
+++ b/drivers/staging/android/ion/ion.h
@@ -168,6 +168,8 @@ struct ion_heap {

/* protect heap statistics */
spinlock_t stat_lock;
+
+ bool no_shrink;
};

/**
diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index aa8d8425be25..ecc22eb870d0 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -114,6 +114,7 @@ static int ion_system_heap_allocate(struct ion_heap *heap,
return -ENOMEM;

INIT_LIST_HEAD(&pages);
+ heap->no_shrink = true;
while (size_remaining > 0) {
page = alloc_largest_available(sys_heap, buffer, size_remaining,
max_order);
@@ -139,6 +140,7 @@ static int ion_system_heap_allocate(struct ion_heap *heap,
}

buffer->sg_table = table;
+ heap->no_shrink = false;
return 0;

free_table:
@@ -146,6 +148,7 @@ static int ion_system_heap_allocate(struct ion_heap *heap,
free_pages:
list_for_each_entry_safe(page, tmp_page, &pages, lru)
free_buffer_page(sys_heap, buffer, page);
+ heap->no_shrink = false;
return -ENOMEM;
}

@@ -200,6 +203,7 @@ static int ion_system_heap_shrink(struct ion_heap *heap, gfp_t gfp_mask,
break;
}
}
+ BUG_ON(heap->no_shrink && nr_total);
return nr_total;
}

----------------------------------------

----------------------------------------
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
struct ion_allocation_data {
unsigned long long len;
unsigned int heap_id_mask;
unsigned int flags;
unsigned int fd;
unsigned int unused;
} data = {
3ULL * 1048576 * 1024, -1, 1, -1, 0
};
int i;

for (i = 0; i < 10; i++) {
if (fork() == 0) {
ioctl(open("/dev/ion", 0, 0), 0xc0184900, &data);
pause();
}
}
return 0;
}
----------------------------------------

----------------------------------------
[ 182.907464][ T7500] ------------[ cut here ]------------
[ 182.907468][ T7500] kernel BUG at drivers/staging/android/ion/ion_system_heap.c:206!
[ 182.907477][ T7500] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[ 182.907481][ T7500] CPU: 4 PID: 7500 Comm: a.out Not tainted 5.2.0-rc5+ #207
[ 182.907483][ T7500] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/13/2018
[ 182.907491][ T7500] RIP: 0010:ion_system_heap_shrink+0xbf/0xd0
[ 182.907495][ T7500] Code: 41 5f 5d c3 e8 02 91 8f fe 8b 75 d4 44 89 ea 48 8b 7d c0 e8 23 0d 00 00 41 29 c5 41 01 c4 45 85 ed 7f a7 eb b4 e8 e1 90 8f fe <0f> 0b 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41
[ 182.907497][ T7500] RSP: 0000:ffffc90001de77d0 EFLAGS: 00010293
[ 182.907501][ T7500] RAX: ffff888212698700 RBX: ffff88822985fba8 RCX: ffffffff82a398af
[ 182.907503][ T7500] RDX: 0000000000000000 RSI: 0000000000140dc2 RDI: ffff888229927b00
[ 182.907506][ T7500] RBP: ffffc90001de7810 R08: 0000000000000000 R09: 0000000000000004
[ 182.907508][ T7500] R10: ffffc90001de7790 R11: 0000000000000001 R12: 0000000000002021
[ 182.907511][ T7500] R13: 0000000000000000 R14: 0000000000000000 R15: ffff88822985fa00
[ 182.907515][ T7500] FS: 00007fe4034934c0(0000) GS:ffff888235d00000(0000) knlGS:0000000000000000
[ 182.907520][ T7500] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 182.907522][ T7500] CR2: 00007fe402f9e5ad CR3: 0000000215075003 CR4: 00000000003606e0
[ 182.907556][ T7500] Call Trace:
[ 182.907562][ T7500] ? order_to_index+0x50/0x50
[ 182.907566][ T7500] ion_heap_shrink_count+0x5b/0x80
[ 182.907572][ T7500] do_shrink_slab+0x66/0x570
[ 182.907578][ T7500] shrink_slab+0x288/0x360
[ 182.907583][ T7500] shrink_node+0x1f6/0x5e0
[ 182.907589][ T7500] do_try_to_free_pages+0x118/0x520
[ 182.907594][ T7500] try_to_free_pages+0x138/0x420
[ 182.907601][ T7500] __alloc_pages_slowpath+0x452/0x1150
[ 182.907610][ T7500] __alloc_pages_nodemask+0x3ac/0x440
[ 182.907615][ T7500] alloc_pages_current+0x7a/0x110
[ 182.907620][ T7500] ion_page_pool_alloc+0x62/0xd0
[ 182.907624][ T7500] ion_system_heap_allocate+0xb4/0x420
[ 182.907628][ T7500] ? ion_ioctl+0x364/0x800
[ 182.907633][ T7500] ion_ioctl+0x332/0x800
[ 182.907641][ T7500] ? _ion_buffer_destroy+0x80/0x80
[ 182.907645][ T7500] do_vfs_ioctl+0xc1/0x8a0
[ 182.907650][ T7500] ? tomoyo_file_ioctl+0x23/0x30
[ 182.907655][ T7500] ksys_ioctl+0x94/0xb0
[ 182.907660][ T7500] __x64_sys_ioctl+0x1e/0x30
[ 182.907665][ T7500] do_syscall_64+0x81/0x2b0
[ 182.907670][ T7500] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 182.907674][ T7500] RIP: 0033:0x7fe402f9e5d7
[ 182.907679][ T7500] Code: Bad RIP value.
[ 182.907681][ T7500] RSP: 002b:00007fff65b39098 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[ 182.907685][ T7500] RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 00007fe402f9e5d7
[ 182.907688][ T7500] RDX: 00007fff65b390a0 RSI: 00000000c0184900 RDI: 0000000000000003
[ 182.907690][ T7500] RBP: 00007fff65b390a0 R08: 00007fe4034934c0 R09: 00007fe403274d80
[ 182.907693][ T7500] R10: 0000000000000000 R11: 0000000000000246 R12: 000055c9049dd720
[ 182.907695][ T7500] R13: 00007fff65b391b0 R14: 0000000000000000 R15: 0000000000000000
[ 182.907699][ T7500] Modules linked in:
[ 182.907738][ T7500] ---[ end trace b9487e8931865499 ]---
[ 182.907745][ T7500] RIP: 0010:ion_system_heap_shrink+0xbf/0xd0
[ 182.907752][ T7500] Code: 41 5f 5d c3 e8 02 91 8f fe 8b 75 d4 44 89 ea 48 8b 7d c0 e8 23 0d 00 00 41 29 c5 41 01 c4 45 85 ed 7f a7 eb b4 e8 e1 90 8f fe <0f> 0b 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41
[ 182.907756][ T7500] RSP: 0000:ffffc90001de77d0 EFLAGS: 00010293
[ 182.907765][ T7500] RAX: ffff888212698700 RBX: ffff88822985fba8 RCX: ffffffff82a398af
[ 182.907771][ T7500] RDX: 0000000000000000 RSI: 0000000000140dc2 RDI: ffff888229927b00
[ 182.907775][ T7500] RBP: ffffc90001de7810 R08: 0000000000000000 R09: 0000000000000004
[ 182.907780][ T7500] R10: ffffc90001de7790 R11: 0000000000000001 R12: 0000000000002021
[ 182.907784][ T7500] R13: 0000000000000000 R14: 0000000000000000 R15: ffff88822985fa00
[ 182.907789][ T7500] FS: 00007fe4034934c0(0000) GS:ffff888235d00000(0000) knlGS:0000000000000000
[ 182.907793][ T7500] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 182.907798][ T7500] CR2: 00007fe402f9e5ad CR3: 0000000215075003 CR4: 00000000003606e0
----------------------------------------

Below is a patch for the original problem reported by syzbot
( https://syzkaller.appspot.com/text?tag=CrashLog&x=11bb246ea00000 ).

----------------------------------------

From e0758655727044753399fb4f7c5f3eb25ac5cccd Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin...@I-love.SAKURA.ne.jp>
Date: Fri, 21 Jun 2019 11:22:51 +0900
Subject: [PATCH] staging: android: ion: Bail out upon SIGKILL when allocating memory.

syzbot found that a thread can stall for minutes inside
ion_system_heap_allocate() after that thread was killed by SIGKILL [1].
Let's check for SIGKILL before doing memory allocation.

[1] https://syzkaller.appspot.com/bug?id=a0e3436829698d5824231251fad9d8e998f94f5e

Signed-off-by: Tetsuo Handa <penguin...@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+8ab2d0...@syzkaller.appspotmail.com>
---
drivers/staging/android/ion/ion_page_pool.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index fd4995fb676e..f85ec5b16b65 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -8,11 +8,14 @@
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/swap.h>
+#include <linux/sched/signal.h>

#include "ion.h"

static inline struct page *ion_page_pool_alloc_pages(struct ion_page_pool *pool)
{
+ if (fatal_signal_pending(current))
+ return NULL;
return alloc_pages(pool->gfp_mask, pool->order);
}

--
2.17.1

Eric Biggers

unread,
Jul 23, 2019, 10:54:25 PM7/23/19
to Tetsuo Handa, Eric Biederman, syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com
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> For more options, visit https://groups.google.com/d/optout.

What happened to this patch? This bug is still occurring.

- Eric

Tetsuo Handa

unread,
Jul 23, 2019, 11:09:08 PM7/23/19
to Eric Biederman, syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com
On 2019/07/24 11:54, Eric Biggers wrote:
>
> What happened to this patch? This bug is still occurring.

Andrew Morton added this patch to the -mm tree.
Should appear in the linux-next tree in a few days.

https://marc.info/?l=linux-mm-commits&m=156391134729795&w=2
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