[syzbot] general protection fault in binder_alloc_print_pages

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 95d10484d66e Add linux-next specific files for 20220817
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=111364f3080000
kernel config: https://syzkaller.appspot.com/x/.config?x=2f5fa747986be53a
dashboard link: https://syzkaller.appspot.com/bug?extid=a75ebe0452711c9e56d9
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=149f9067080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=161a9fc3080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a75ebe...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000025: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000128-0x000000000000012f]
CPU: 0 PID: 3609 Comm: syz-executor323 Not tainted 6.0.0-rc1-next-20220817-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
RIP: 0010:__lock_acquire+0xd83/0x56d0 kernel/locking/lockdep.c:4923
Code: 9b 0e 41 bf 01 00 00 00 0f 86 c8 00 00 00 89 05 63 56 9b 0e e9 bd 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 4e 31 00 00 49 81 3e 60 84 51 8f 0f 84 4c f3 ff
RSP: 0018:ffffc900038df6a0 EFLAGS: 00010002
RAX: dffffc0000000000 RBX: 1ffff9200071bf03 RCX: 0000000000000001
RDX: 0000000000000025 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: fffffbfff1bbd60a R11: 0000000000000000 R12: 0000000000000000
R13: ffff888026b68000 R14: 0000000000000128 R15: 0000000000000001
FS: 0000555555ed8300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffb27bfa130 CR3: 000000001e324000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
lock_acquire kernel/locking/lockdep.c:5666 [inline]
lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
down_read+0x98/0x450 kernel/locking/rwsem.c:1499
mmap_read_lock include/linux/mmap_lock.h:117 [inline]
binder_alloc_print_pages+0x65/0x420 drivers/android/binder_alloc.c:936
print_binder_proc_stats drivers/android/binder.c:6289 [inline]
stats_show+0x417/0x620 drivers/android/binder.c:6352
seq_read_iter+0x4f5/0x1280 fs/seq_file.c:230
seq_read+0x16d/0x210 fs/seq_file.c:162
full_proxy_read+0x118/0x180 fs/debugfs/file.c:231
do_loop_readv_writev fs/read_write.c:750 [inline]
do_loop_readv_writev fs/read_write.c:737 [inline]
do_iter_read+0x4f8/0x750 fs/read_write.c:792
vfs_readv+0xe5/0x150 fs/read_write.c:910
do_preadv fs/read_write.c:1002 [inline]
__do_sys_preadv fs/read_write.c:1052 [inline]
__se_sys_preadv fs/read_write.c:1047 [inline]
__x64_sys_preadv+0x22b/0x310 fs/read_write.c:1047
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ffb27b890c9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe668da498 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007ffb27b890c9
RDX: 0000000000000001 RSI: 0000000020000080 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 00007ffb27bf6e40
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe668da4d0
R13: 00007ffe668da4c0 R14: 00007ffe668da4b0 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__lock_acquire+0xd83/0x56d0 kernel/locking/lockdep.c:4923
Code: 9b 0e 41 bf 01 00 00 00 0f 86 c8 00 00 00 89 05 63 56 9b 0e e9 bd 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 4e 31 00 00 49 81 3e 60 84 51 8f 0f 84 4c f3 ff
RSP: 0018:ffffc900038df6a0 EFLAGS: 00010002
RAX: dffffc0000000000 RBX: 1ffff9200071bf03 RCX: 0000000000000001
RDX: 0000000000000025 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: fffffbfff1bbd60a R11: 0000000000000000 R12: 0000000000000000
R13: ffff888026b68000 R14: 0000000000000128 R15: 0000000000000001
FS: 0000555555ed8300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffb27bfa130 CR3: 000000001e324000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 2 bytes skipped:
0: 41 bf 01 00 00 00 mov $0x1,%r15d
6: 0f 86 c8 00 00 00 jbe 0xd4
c: 89 05 63 56 9b 0e mov %eax,0xe9b5663(%rip) # 0xe9b5675
12: e9 bd 00 00 00 jmpq 0xd4
17: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
1e: fc ff df
21: 4c 89 f2 mov %r14,%rdx
24: 48 c1 ea 03 shr $0x3,%rdx
* 28: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2c: 0f 85 4e 31 00 00 jne 0x3180
32: 49 81 3e 60 84 51 8f cmpq $0xffffffff8f518460,(%r14)
39: 0f .byte 0xf
3a: 84 4c f3 ff test %cl,-0x1(%rbx,%rsi,8)


---
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[Hillf Danton]

On Sun, 21 Aug 2022 01:55:32 -0700

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 95d10484d66e Add linux-next specific files for 20220817
> git tree: linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=111364f3080000
> kernel config: https://syzkaller.appspot.com/x/.config?x=2f5fa747986be53a
> dashboard link: https://syzkaller.appspot.com/bug?extid=a75ebe0452711c9e56d9
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=149f9067080000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=161a9fc3080000

See if the binder_alloc is fully initialized.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git 95d10484d66e

--- a/drivers/android/binder_alloc.c 2022-08-21 19:41:10.572060800 +0800
+++ b/drivers/android/binder_alloc.c 2022-08-21 20:03:53.241022700 +0800
@@ -402,6 +402,8 @@ static struct binder_buffer *binder_allo
size_t size, data_offsets_size;
int ret;

+ if (!alloc->vma_addr)
+ return ERR_PTR(-ESRCH);
mmap_read_lock(alloc->vma_vm_mm);
if (!binder_alloc_get_vma(alloc)) {
mmap_read_unlock(alloc->vma_vm_mm);
@@ -933,6 +935,8 @@ void binder_alloc_print_pages(struct seq
* read inconsistent state.
*/

+ if (!alloc->vma_addr)
+ goto out;
mmap_read_lock(alloc->vma_vm_mm);
if (binder_alloc_get_vma(alloc) == NULL)
goto uninitialized;
@@ -949,6 +953,7 @@ void binder_alloc_print_pages(struct seq

uninitialized:
mmap_read_unlock(alloc->vma_vm_mm);
+out:
mutex_unlock(&alloc->mutex);
seq_printf(m, " pages: %d:%d:%d\n", active, lru, free);
seq_printf(m, " pages high watermark: %zu\n", alloc->pages_high);
--

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+a75ebe...@syzkaller.appspotmail.com

Tested on:

commit: 95d10484 Add linux-next specific files for 20220817
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=15570865080000

kernel config: https://syzkaller.appspot.com/x/.config?x=2f5fa747986be53a
dashboard link: https://syzkaller.appspot.com/bug?extid=a75ebe0452711c9e56d9
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=153db6eb080000

Note: testing is done by a robot and is best-effort only.