general protection fault in tcp_splice_read

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 69b94dd6 Linux 4.14.189
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=140a1528900000
kernel config: https://syzkaller.appspot.com/x/.config?x=80d63ff414fa81b0
dashboard link: https://syzkaller.appspot.com/bug?extid=e0d111086728da125162
compiler: gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e0d111...@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
kasan: CONFIG_KASAN_INLINE enabled
Modules linked in:
CPU: 0 PID: 18925 Comm: syz-executor.4 Not tainted 4.14.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff888212c2c5c0 task.stack: ffff888155aa0000
RIP: 0010:tcp_splice_read+0x123/0x950 net/ipv4/tcp.c:779
RSP: 0018:ffff888155aa7c40 EFLAGS: 00010206
kasan: GPF could be caused by NULL-ptr deref or user memory access
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 1ffff110425859d7
RDX: 000000000000000f RSI: ffff888212c2ce98 RDI: 0000000000000078
RBP: ffff8880326f4a80 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888155aa7ea8
R13: 0000000000000000 R14: ffff888090eae540 R15: 0000000000000000
FS: 00007f0219002700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e154127970 CR3: 0000000210e1a000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
smc_splice_read+0x16c/0x1c0 net/smc/af_smc.c:1304
sock_splice_read+0xa6/0xe0 net/socket.c:883
do_splice_to+0xfb/0x140 fs/splice.c:880
do_splice fs/splice.c:1173 [inline]
SYSC_splice fs/splice.c:1402 [inline]
SyS_splice+0x104a/0x1380 fs/splice.c:1382
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45c369
RSP: 002b:00007f0219001c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 0000000000032240 RCX: 000000000045c369
RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 000000000078bf58 R08: 0000000000000006 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007fffc3c41c8f R14: 00007f02190029c0 R15: 000000000078bf0c
Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c9 07 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 5b 18 48 8d 7b 78 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e db 06 00 00 45 31 e4 f6 43
RIP: tcp_splice_read+0x123/0x950 net/ipv4/tcp.c:779 RSP: ffff888155aa7c40
general protection fault: 0000 [#2] PREEMPT SMP KASAN
---[ end trace 41a6619d89ea92e3 ]---
Modules linked in:
CPU: 1 PID: 18938 Comm: syz-executor.0 Tainted: G D 4.14.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011


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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 69b94dd6 Linux 4.14.189
git tree: linux-4.14.y

console output: https://syzkaller.appspot.com/x/log.txt?x=1653cc9c900000

kernel config: https://syzkaller.appspot.com/x/.config?x=80d63ff414fa81b0
dashboard link: https://syzkaller.appspot.com/bug?extid=e0d111086728da125162
compiler: gcc (GCC) 10.1.0-syz 20200507

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13fe0ec4900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17f4b9df100000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e0d111...@syzkaller.appspotmail.com

audit: type=1400 audit(1595800528.436:8): avc: denied { execmem } for pid=6338 comm="syz-executor004" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN

Modules linked in:
CPU: 0 PID: 6338 Comm: syz-executor004 Not tainted 4.14.189-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

task: ffff888097b06600 task.stack: ffff888086e70000

RIP: 0010:tcp_splice_read+0x123/0x950 net/ipv4/tcp.c:779

RSP: 0018:ffff888086e77c40 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 1ffff11012f60ddf
RDX: 000000000000000f RSI: ffff888097b06ed8 RDI: 0000000000000078
RBP: ffff888097c8b500 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888086e77ea8
R13: 0000000000000000 R14: ffff888097aa3580 R15: 0000000000000000
FS: 00000000016d7880(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00000000200000c0 CR3: 00000000a48b9000 CR4: 00000000001406f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
smc_splice_read+0x16c/0x1c0 net/smc/af_smc.c:1304
sock_splice_read+0xa6/0xe0 net/socket.c:883
do_splice_to+0xfb/0x140 fs/splice.c:880
do_splice fs/splice.c:1173 [inline]
SYSC_splice fs/splice.c:1402 [inline]
SyS_splice+0x104a/0x1380 fs/splice.c:1382
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb

RIP: 0033:0x4402c9
RSP: 002b:00007ffcc51ed9c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402c9

RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000005

RBP: 00000000006ca018 R08: 0000000000000006 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401ad0
R13: 0000000000401b60 R14: 0000000000000000 R15: 0000000000000000

Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c9 07 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 5b 18 48 8d 7b 78 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e db 06 00 00 45 31 e4 f6 43

RIP: tcp_splice_read+0x123/0x950 net/ipv4/tcp.c:779 RSP: ffff888086e77c40
---[ end trace 4547e70882029cec ]---