[syzbot] general protection fault in release_udmabuf

From: syzbot
Date: Thu Aug 18 2022 - 20:09:31 EST

Hello,

syzbot found the following issue on:

HEAD commit: 7ebfc85e2cd7 Merge tag 'net-6.0-rc1' of git://git.kernel.o..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1331f447080000
kernel config: https://syzkaller.appspot.com/x/.config?x=924833c12349a8c0
dashboard link: https://syzkaller.appspot.com/bug?extid=c80e9ef5d8bb45894db0
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=1601336b080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16d3292d080000

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16e01a3d080000
final oops: https://syzkaller.appspot.com/x/report.txt?x=15e01a3d080000
console output: https://syzkaller.appspot.com/x/log.txt?x=11e01a3d080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c80e9ef5d8bb45894db0@xxxxxxxxxxxxxxxxxxxxxxxxx

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 3609 Comm: syz-executor487 Not tainted 5.19.0-syzkaller-13930-g7ebfc85e2cd7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
RIP: 0010:dma_unmap_sgtable include/linux/dma-mapping.h:378 [inline]
RIP: 0010:put_sg_table drivers/dma-buf/udmabuf.c:89 [inline]
RIP: 0010:release_udmabuf+0xcb/0x4f0 drivers/dma-buf/udmabuf.c:114
Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 2b 04 00 00 48 8d 7d 0c 4c 8b 63 30 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 e2
RSP: 0018:ffffc900037efd30 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffffffff8cb67800 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff84ad27e0 RDI: 0000000000000000
RBP: fffffffffffffff4 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 000000000008c07c R12: ffff88801fa05000
R13: ffff888073db07e8 R14: ffff888025c25440 R15: 0000000000000000
FS: 0000555555fc4300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc1c0ce06e4 CR3: 00000000715e6000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
dma_buf_release+0x157/0x2d0 drivers/dma-buf/dma-buf.c:78
__dentry_kill+0x42b/0x640 fs/dcache.c:612
dentry_kill fs/dcache.c:733 [inline]
dput+0x806/0xdb0 fs/dcache.c:913
__fput+0x39c/0x9d0 fs/file_table.c:333
task_work_run+0xdd/0x1a0 kernel/task_work.c:177
ptrace_notify+0x114/0x140 kernel/signal.c:2353
ptrace_report_syscall include/linux/ptrace.h:420 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:482 [inline]
syscall_exit_work kernel/entry/common.c:249 [inline]
syscall_exit_to_user_mode_prepare+0x129/0x280 kernel/entry/common.c:276
__syscall_exit_to_user_mode_work kernel/entry/common.c:281 [inline]
syscall_exit_to_user_mode+0x9/0x50 kernel/entry/common.c:294
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fc1c0c35b6b
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
RSP: 002b:00007ffd78a06090 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007fc1c0c35b6b
RDX: 0000000020000280 RSI: 0000000040086200 RDI: 0000000000000006
RBP: 0000000000000007 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 000000000000000c
R13: 0000000000000003 R14: 00007fc1c0cfe4a0 R15: 00007ffd78a06140
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dma_unmap_sgtable include/linux/dma-mapping.h:378 [inline]
RIP: 0010:put_sg_table drivers/dma-buf/udmabuf.c:89 [inline]
RIP: 0010:release_udmabuf+0xcb/0x4f0 drivers/dma-buf/udmabuf.c:114
Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 2b 04 00 00 48 8d 7d 0c 4c 8b 63 30 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 e2
RSP: 0018:ffffc900037efd30 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffffffff8cb67800 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff84ad27e0 RDI: 0000000000000000
RBP: fffffffffffffff4 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 000000000008c07c R12: ffff88801fa05000
R13: ffff888073db07e8 R14: ffff888025c25440 R15: 0000000000000000
FS: 0000555555fc4300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564b46eeb2c8 CR3: 00000000715e6000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 48 89 fa mov %rdi,%rdx
3: 48 c1 ea 03 shr $0x3,%rdx
7: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
b: 0f 85 2b 04 00 00 jne 0x43c
11: 48 8d 7d 0c lea 0xc(%rbp),%rdi
15: 4c 8b 63 30 mov 0x30(%rbx),%r12
19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
20: fc ff df
23: 48 89 fa mov %rdi,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx <-- trapping instruction
2e: 48 89 f8 mov %rdi,%rax
31: 83 e0 07 and $0x7,%eax
34: 83 c0 03 add $0x3,%eax
37: 38 d0 cmp %dl,%al
39: 7c 08 jl 0x43
3b: 84 d2 test %dl,%dl
3d: 0f .byte 0xf
3e: 85 e2 test %esp,%edx


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