linux-kernel - Re: [PATCH] riscv/mm: Add handling for VM_FAULT_SIGSEGV in mm_fault

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAHVXubh2MawWGzcL38DPnj2Xa=ZGNr6JK3of3v=eSEOkMeu8Bw@mail.gmail.com>
Date: Wed, 31 Jul 2024 09:10:33 +0200
From: Alexandre Ghiti <alexghiti@...osinc.com>
To: Zhe Qiao <qiaozhe@...as.ac.cn>
Cc: paul.walmsley@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu, 
	surenb@...gle.com, akpm@...ux-foundation.org, wangkefeng.wang@...wei.com, 
	willy@...radead.org, linux-riscv@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv/mm: Add handling for VM_FAULT_SIGSEGV in mm_fault_error()

Hi Zhe,

On Wed, Jul 31, 2024 at 5:26 AM Zhe Qiao <qiaozhe@...as.ac.cn> wrote:
>
> Add processing for VM_CAULT_SIGSEGV to mm_fault_error () to avoid
> direct execution of BUG().

Sorry to bother you again, but since there is a typo
(s/VM_CAULT_SIGSEGV/VM_FAULT_SIGSEGV), do you mind rephrasing the
commit log like this (or similar)?

"Handle VM_FAULT_SIGSEGV in the page fault path so that we correctly
kill the process and we don't BUG() the kernel."

>
> Fixes: 07037db5d479 ("RISC-V: Paging and MMU")
> Signed-off-by: Zhe Qiao <qiaozhe@...as.ac.cn>
> ---
>  arch/riscv/mm/fault.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
> index 5224f3733802..a9f2b4af8f3f 100644
> --- a/arch/riscv/mm/fault.c
> +++ b/arch/riscv/mm/fault.c
> @@ -61,26 +61,27 @@ static inline void no_context(struct pt_regs *regs, unsigned long addr)
>
>  static inline void mm_fault_error(struct pt_regs *regs, unsigned long addr, vm_fault_t fault)
>  {
> +       if (!user_mode(regs)) {
> +               no_context(regs, addr);
> +               return;
> +       }
> +
>         if (fault & VM_FAULT_OOM) {
>                 /*
>                  * We ran out of memory, call the OOM killer, and return the userspace
>                  * (which will retry the fault, or kill us if we got oom-killed).
>                  */
> -               if (!user_mode(regs)) {
> -                       no_context(regs, addr);
> -                       return;
> -               }
>                 pagefault_out_of_memory();
>                 return;
>         } else if (fault & (VM_FAULT_SIGBUS | VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) {
>                 /* Kernel mode? Handle exceptions or die */
> -               if (!user_mode(regs)) {
> -                       no_context(regs, addr);
> -                       return;
> -               }
>                 do_trap(regs, SIGBUS, BUS_ADRERR, addr);
>                 return;
> +       } else if (fault & VM_FAULT_SIGSEGV) {
> +               do_trap(regs, SIGSEGV, SEGV_MAPERR, addr);
> +               return;
>         }
> +
>         BUG();
>  }
>
> --
> 2.43.0
>

That's a very good catch, good job! You can add:

Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>

Thanks,

Alex