2022-08-11 10:39:03

by Dan Carpenter

[permalink] [raw]
Subject: arch/riscv/kernel/traps.c:48 die() warn: variable dereferenced before check 'regs' (see line 46)

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: f41445645ab5d172e6090d00c332c335d8dba337
commit: 3f1901110a89b0e2e13adb2ac8d1a7102879ea98 RISC-V: Add fast call path of crash_kexec()
config: riscv-randconfig-m031-20220810 (https://download.01.org/0day-ci/archive/20220811/[email protected]/config)
compiler: riscv64-linux-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email protected]>
Reported-by: Dan Carpenter <[email protected]>

smatch warnings:
arch/riscv/kernel/traps.c:48 die() warn: variable dereferenced before check 'regs' (see line 46)

vim +/regs +48 arch/riscv/kernel/traps.c

76d2a0493a17d4 Palmer Dabbelt 2017-07-10 31 void die(struct pt_regs *regs, const char *str)
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 32 {
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 33 static int die_counter;
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 34 int ret;
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 35
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 36 oops_enter();
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 37
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 38 spin_lock_irq(&die_lock);
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 39 console_verbose();
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 40 bust_spinlocks(1);
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 41
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 42 pr_emerg("%s [#%d]\n", str, ++die_counter);
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 43 print_modules();
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 44 show_regs(regs);
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 45
a4c3733d32a72f Christoph Hellwig 2019-10-28 @46 ret = notify_die(DIE_OOPS, str, regs, 0, regs->cause, SIGSEGV);
^^^^^^^^^^^
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 47
3f1901110a89b0 Xianting Tian 2022-06-06 @48 if (regs && kexec_should_crash(current))
^^^^

Delete this NULL check.

3f1901110a89b0 Xianting Tian 2022-06-06 49 crash_kexec(regs);
3f1901110a89b0 Xianting Tian 2022-06-06 50
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 51 bust_spinlocks(0);
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 52 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 53 spin_unlock_irq(&die_lock);
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 54 oops_exit();
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 55
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 56 if (in_interrupt())
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 57 panic("Fatal exception in interrupt");
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 58 if (panic_on_oops)
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 59 panic("Fatal exception");
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 60 if (ret != NOTIFY_STOP)
0e25498f8cd43c Eric W. Biederman 2021-06-28 61 make_task_dead(SIGSEGV);
76d2a0493a17d4 Palmer Dabbelt 2017-07-10 62 }

--
0-DAY CI Kernel Test Service
https://01.org/lkp


2022-08-11 11:01:00

by Xianting Tian

[permalink] [raw]
Subject: Re: arch/riscv/kernel/traps.c:48 die() warn: variable dereferenced before check 'regs' (see line 46)


在 2022/8/11 下午6:33, Dan Carpenter 写道:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: f41445645ab5d172e6090d00c332c335d8dba337
> commit: 3f1901110a89b0e2e13adb2ac8d1a7102879ea98 RISC-V: Add fast call path of crash_kexec()
> config: riscv-randconfig-m031-20220810 (https://download.01.org/0day-ci/archive/20220811/[email protected]/config)
> compiler: riscv64-linux-gcc (GCC) 12.1.0
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <[email protected]>
> Reported-by: Dan Carpenter <[email protected]>
>
> smatch warnings:
> arch/riscv/kernel/traps.c:48 die() warn: variable dereferenced before check 'regs' (see line 46)
>
> vim +/regs +48 arch/riscv/kernel/traps.c
>
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 31 void die(struct pt_regs *regs, const char *str)
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 32 {
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 33 static int die_counter;
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 34 int ret;
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 35
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 36 oops_enter();
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 37
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 38 spin_lock_irq(&die_lock);
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 39 console_verbose();
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 40 bust_spinlocks(1);
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 41
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 42 pr_emerg("%s [#%d]\n", str, ++die_counter);
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 43 print_modules();
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 44 show_regs(regs);
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 45
> a4c3733d32a72f Christoph Hellwig 2019-10-28 @46 ret = notify_die(DIE_OOPS, str, regs, 0, regs->cause, SIGSEGV);
> ^^^^^^^^^^^
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 47
> 3f1901110a89b0 Xianting Tian 2022-06-06 @48 if (regs && kexec_should_crash(current))
> ^^^^
>
> Delete this NULL check.
thanks,  I will send another fixup patch to fix the issue, is it OK?
>
> 3f1901110a89b0 Xianting Tian 2022-06-06 49 crash_kexec(regs);
> 3f1901110a89b0 Xianting Tian 2022-06-06 50
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 51 bust_spinlocks(0);
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 52 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 53 spin_unlock_irq(&die_lock);
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 54 oops_exit();
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 55
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 56 if (in_interrupt())
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 57 panic("Fatal exception in interrupt");
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 58 if (panic_on_oops)
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 59 panic("Fatal exception");
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 60 if (ret != NOTIFY_STOP)
> 0e25498f8cd43c Eric W. Biederman 2021-06-28 61 make_task_dead(SIGSEGV);
> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 62 }
>

2022-09-20 20:26:10

by Palmer Dabbelt

[permalink] [raw]
Subject: Re: arch/riscv/kernel/traps.c:48 die() warn: variable dereferenced before check 'regs' (see line 46)

On Thu, 11 Aug 2022 03:42:28 PDT (-0700), [email protected] wrote:
>
> 在 2022/8/11 下午6:33, Dan Carpenter 写道:
>> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>> head: f41445645ab5d172e6090d00c332c335d8dba337
>> commit: 3f1901110a89b0e2e13adb2ac8d1a7102879ea98 RISC-V: Add fast call path of crash_kexec()
>> config: riscv-randconfig-m031-20220810 (https://download.01.org/0day-ci/archive/20220811/[email protected]/config)
>> compiler: riscv64-linux-gcc (GCC) 12.1.0
>>
>> If you fix the issue, kindly add following tag where applicable
>> Reported-by: kernel test robot <[email protected]>
>> Reported-by: Dan Carpenter <[email protected]>
>>
>> smatch warnings:
>> arch/riscv/kernel/traps.c:48 die() warn: variable dereferenced before check 'regs' (see line 46)
>>
>> vim +/regs +48 arch/riscv/kernel/traps.c
>>
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 31 void die(struct pt_regs *regs, const char *str)
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 32 {
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 33 static int die_counter;
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 34 int ret;
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 35
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 36 oops_enter();
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 37
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 38 spin_lock_irq(&die_lock);
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 39 console_verbose();
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 40 bust_spinlocks(1);
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 41
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 42 pr_emerg("%s [#%d]\n", str, ++die_counter);
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 43 print_modules();
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 44 show_regs(regs);
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 45
>> a4c3733d32a72f Christoph Hellwig 2019-10-28 @46 ret = notify_die(DIE_OOPS, str, regs, 0, regs->cause, SIGSEGV);
>> ^^^^^^^^^^^
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 47
>> 3f1901110a89b0 Xianting Tian 2022-06-06 @48 if (regs && kexec_should_crash(current))
>> ^^^^
>>
>> Delete this NULL check.
> thanks,  I will send another fixup patch to fix the issue, is it OK?

You're always welcome to send fixes, but I didn't see anything so I just
sent along https://lore.kernel.org/r/[email protected]/

>>
>> 3f1901110a89b0 Xianting Tian 2022-06-06 49 crash_kexec(regs);
>> 3f1901110a89b0 Xianting Tian 2022-06-06 50
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 51 bust_spinlocks(0);
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 52 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 53 spin_unlock_irq(&die_lock);
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 54 oops_exit();
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 55
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 56 if (in_interrupt())
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 57 panic("Fatal exception in interrupt");
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 58 if (panic_on_oops)
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 59 panic("Fatal exception");
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 60 if (ret != NOTIFY_STOP)
>> 0e25498f8cd43c Eric W. Biederman 2021-06-28 61 make_task_dead(SIGSEGV);
>> 76d2a0493a17d4 Palmer Dabbelt 2017-07-10 62 }
>>

2022-09-21 02:17:23

by Xianting Tian

[permalink] [raw]
Subject: Re: arch/riscv/kernel/traps.c:48 die() warn: variable dereferenced before check 'regs' (see line 46)


在 2022/9/21 上午4:06, Palmer Dabbelt 写道:
> On Thu, 11 Aug 2022 03:42:28 PDT (-0700),
> [email protected] wrote:
>>
>> 在 2022/8/11 下午6:33, Dan Carpenter 写道:
>>> tree:
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>>> master
>>> head:   f41445645ab5d172e6090d00c332c335d8dba337
>>> commit: 3f1901110a89b0e2e13adb2ac8d1a7102879ea98 RISC-V: Add fast
>>> call path of crash_kexec()
>>> config: riscv-randconfig-m031-20220810
>>> (https://download.01.org/0day-ci/archive/20220811/[email protected]/config)
>>> compiler: riscv64-linux-gcc (GCC) 12.1.0
>>>
>>> If you fix the issue, kindly add following tag where applicable
>>> Reported-by: kernel test robot <[email protected]>
>>> Reported-by: Dan Carpenter <[email protected]>
>>>
>>> smatch warnings:
>>> arch/riscv/kernel/traps.c:48 die() warn: variable dereferenced
>>> before check 'regs' (see line 46)
>>>
>>> vim +/regs +48 arch/riscv/kernel/traps.c
>>>
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  31  void die(struct
>>> pt_regs *regs, const char *str)
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  32  {
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  33      static int
>>> die_counter;
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  34      int ret;
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  35
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  36 oops_enter();
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  37
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  38
>>> spin_lock_irq(&die_lock);
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  39 console_verbose();
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  40 bust_spinlocks(1);
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  41
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  42 pr_emerg("%s
>>> [#%d]\n", str, ++die_counter);
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  43 print_modules();
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  44 show_regs(regs);
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  45
>>> a4c3733d32a72f Christoph Hellwig 2019-10-28 @46      ret =
>>> notify_die(DIE_OOPS, str, regs, 0, regs->cause, SIGSEGV);
>>> ^^^^^^^^^^^
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  47
>>> 3f1901110a89b0 Xianting Tian     2022-06-06 @48      if (regs &&
>>> kexec_should_crash(current))
>>> ^^^^
>>>
>>> Delete this NULL check.
>> thanks,  I will send another fixup patch to fix the issue, is it OK?
>
> You're always welcome to send fixes, but I didn't see anything so I
> just sent along
> https://lore.kernel.org/r/[email protected]/
Thanks Palmer for the fix :)
>
>>>
>>> 3f1901110a89b0 Xianting Tian     2022-06-06  49 crash_kexec(regs);
>>> 3f1901110a89b0 Xianting Tian     2022-06-06  50
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  51 bust_spinlocks(0);
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  52 add_taint(TAINT_DIE,
>>> LOCKDEP_NOW_UNRELIABLE);
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  53
>>> spin_unlock_irq(&die_lock);
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  54 oops_exit();
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  55
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  56      if
>>> (in_interrupt())
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  57 panic("Fatal
>>> exception in interrupt");
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  58      if (panic_on_oops)
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  59 panic("Fatal
>>> exception");
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  60      if (ret !=
>>> NOTIFY_STOP)
>>> 0e25498f8cd43c Eric W. Biederman 2021-06-28  61
>>> make_task_dead(SIGSEGV);
>>> 76d2a0493a17d4 Palmer Dabbelt    2017-07-10  62  }
>>>