panic: UBSa[ 57.ADDR] n: Undefined Behavior in /syzkaller/managers/netbsd-kubsan/kernel/sys/arch/amd64/amd64/process_ma

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: ff77761d switch powerpc64 to GCC 8.
git tree: netbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=12da57f6e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=824b23e1f4b6c76b
dashboard link: https://syzkaller.appspot.com/bug?extid=b8fe96ff3932730172b8

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+b8fe96...@syzkaller.appspotmail.com

[ 57.3769402] panic: UBSa[ 57.3869537] n: Undefined Behavior in
/syzkaller/managers/netbsd-kubsan/kernel/sys/arch/amd64/amd64/process_machdep.c:157:2,
member access within misaligned address 0xffffd800b3a978c8 for type 'struct
fpreg' which requires 16 byte alignment

[ 57.4069593] cpu1: Begin traceback...
[ 57.4269785] vpanic() at netbsd:vpanic+0x2aa sys/kern/subr_prf.c:336
[ 57.4870350] isAlreadyReported() at netbsd:isAlreadyReported
[ 57.5470901] HandleTypeMismatch.part.1() at
netbsd:HandleTypeMismatch.part.1+0xcc
[ 57.6071444] HandleTypeMismatch() at netbsd:HandleTypeMismatch+0x7b
sys/../common/lib/libc/misc/ubsan.c:408
[ 57.6571895] process_read_fpregs() at netbsd:process_read_fpregs+0x3d
sys/arch/amd64/amd64/process_machdep.c:157
[ 57.7172464] proc_regio() at netbsd:proc_regio+0x164
sys/kern/sys_ptrace_common.c:1475
[ 57.7773007] process_dofpregs() at netbsd:process_dofpregs+0xa7
sys/kern/sys_ptrace_common.c:1563
[ 57.8373563] do_ptrace() at netbsd:do_ptrace+0x12be ptrace_regs
sys/kern/sys_ptrace_common.c:894 [inline]
[ 57.8373563] do_ptrace() at netbsd:do_ptrace+0x12be
sys/kern/sys_ptrace_common.c:1426
[ 57.8873997] sys_ptrace() at netbsd:sys_ptrace+0x4f
sys/kern/sys_ptrace.c:218
[ 57.9474558] sys___syscall() at netbsd:sys___syscall+0x1c8 sy_call
sys/sys/syscallvar.h:65 [inline]
[ 57.9474558] sys___syscall() at netbsd:sys___syscall+0x1c8
sys/kern/sys_syscall.c:77
[ 58.0075121] syscall() at netbsd:syscall+0x29a sy_call
sys/sys/syscallvar.h:65 [inline]
[ 58.0075121] syscall() at netbsd:syscall+0x29a sy_invoke
sys/sys/syscallvar.h:94 [inline]
[ 58.0075121] syscall() at netbsd:syscall+0x29a
sys/arch/x86/x86/syscall.c:138
[ 58.0175215] --- syscall (number 198) ---
[ 58.0275280] Skipping crash dump on recursive panic
[ 58.0275280] panic: UBSan: Undefined Behavior in
/syzkaller/managers/netbsd-kubsan/kernel/sys/arch/amd64/amd64/db_machdep.c:153:24,
member access within misaligned address 0x4 for type 'struct x86_64_frame'
which requires 8 byte alignment

[ 58.0475456] Faulted in mid-traceback; aborting...
[ 58.0575551] fatal breakpoint trap in supervisor mode
[ 58.0575551] trap type 1 code 0 rip 0xffffffff8021dddd cs 0x8 rflags
0x286 cr2 0x628070 ilevel 0x8 rsp 0xffffd800b3a964b0
[ 58.0675659] curlwp 0xfffffe989454d600 pid 563.3 lowest kstack
0xffffd800b3a942c0
Stopped in pid 563.3 (syz-executor.3) at netbsd:breakpoint+0x5:
leave
?
breakpoint() at netbsd:breakpoint+0x5
db_panic() at netbsd:db_panic+0x109 sys/ddb/db_panic.c:67
vpanic() at netbsd:vpanic+0x2aa sys/kern/subr_prf.c:336
isAlreadyReported() at netbsd:isAlreadyReported
HandleTypeMismatch.part.1() at netbsd:HandleTypeMismatch.part.1+0xcc
HandleTypeMismatch() at netbsd:HandleTypeMismatch+0x7b
sys/../common/lib/libc/misc/ubsan.c:408
db_nextframe() at netbsd:db_nextframe+0x6f6
sys/arch/amd64/amd64/db_machdep.c:153
db_stack_trace_print() at netbsd:db_stack_trace_print+0x2c4
sys/arch/x86/x86/db_trace.c:277
db_panic() at netbsd:db_panic+0xa3 x86_curcpu
sys/arch/amd64/compile/obj/GENERIC_SYZKALLER/./machine/cpu.h:67 [inline]
db_panic() at netbsd:db_panic+0xa3 sys/ddb/db_panic.c:57
vpanic() at netbsd:vpanic+0x2aa sys/kern/subr_prf.c:336
isAlreadyReported() at netbsd:isAlreadyReported
HandleTypeMismatch.part.1() at netbsd:HandleTypeMismatch.part.1+0xcc
HandleTypeMismatch() at netbsd:HandleTypeMismatch+0x7b
sys/../common/lib/libc/misc/ubsan.c:408
process_read_fpregs() at netbsd:process_read_fpregs+0x3d
sys/arch/amd64/amd64/process_machdep.c:157
proc_regio() at netbsd:proc_regio+0x164 sys/kern/sys_ptrace_common.c:1475
process_dofpregs() at netbsd:process_dofpregs+0xa7
sys/kern/sys_ptrace_common.c:1563
do_ptrace() at netbsd:do_ptrace+0x12be ptrace_regs
sys/kern/sys_ptrace_common.c:894 [inline]
do_ptrace() at netbsd:do_ptrace+0x12be sys/kern/sys_ptrace_common.c:1426
sys_ptrace() at netbsd:sys_ptrace+0x4f sys/kern/sys_ptrace.c:218
sys___syscall() at netbsd:sys___syscall+0x1c8 sy_call
sys/sys/syscallvar.h:65 [inline]
sys___syscall() at netbsd:sys___syscall+0x1c8 sys/kern/sys_syscall.c:77
syscall() at netbsd:syscall+0x29a sy_call sys/sys/syscallvar.h:65 [inline]
syscall() at netbsd:syscall+0x29a sy_invoke sys/sys/syscallvar.h:94 [inline]
syscall() at netbsd:syscall+0x29a sys/arch/x86/x86/syscall.c:138
--- syscall (number 198) ---
[ 58.0775743] Skipping crash dump on recursive panic
[ 58.0775743] panic: UBSan: Undefined Behavior in
/syzkaller/managers/netbsd-kubsan/kernel/sys/arch/amd64/amd64/db_machdep.c:154:14,
member access within misaligned address 0x4 for type 'struct x86_64_frame'
which requires 8 byte alignment

[ 58.0775743] Faulted in mid-traceback; aborting...
[ 58.0775743] fatal breakpoint trap in supervisor mode
[ 58.0775743] trap type 1 code 0 rip 0xffffffff8021dddd cs 0x8 rflags
0x286 cr2 0x628070 ilevel 0x8 rsp 0xffffd800b3a951b0
[ 58.0775743] curlwp 0xfffffe989454d600 pid 563.3 lowest kstack
0xffffd800b3a942c0
Stopped in pid 563.3 (syz-executor.3) at netbsd:breakpoint+0x5:
leave


---
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[Kamil Rytarowski]

On 18.11.2019 21:12, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    ff77761d switch powerpc64 to GCC 8.
> git tree:       netbsd
> console output: https://syzkaller.appspot.com/x/log.txt?x=12da57f6e00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=824b23e1f4b6c76b
> dashboard link:
> https://syzkaller.appspot.com/bug?extid=b8fe96ff3932730172b8
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+b8fe96...@syzkaller.appspotmail.com
>
> [  57.3769402] panic: UBSa[  57.3869537] n: Undefined Behavior in
> /syzkaller/managers/netbsd-kubsan/kernel/sys/arch/amd64/amd64/process_machdep.c:157:2,
> member access within misaligned address 0xffffd800b3a978c8 for type
> 'struct fpreg' which requires 16 byte alignment
>

This should fix the problem:

http://netbsd.org/~kamil/patch-00197-buf-align16.txt

I will test it tomorrow.

> [  57.4069593] cpu1: Begin traceback...

[Maxime Villard]

dup but garbage, close

#syz invalid