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Fri, 16 Apr 2021 08:41:33 -0400 X-MC-Unique: LLFz2bKtMt6Sx_m4DCBn4A-1 Received: by mail.kernel.org (Postfix) with ESMTPSA id 67EF2610E6; Fri, 16 Apr 2021 12:33:25 +0000 (UTC) Date: Fri, 16 Apr 2021 13:33:22 +0100 From: Catalin Marinas To: He Zhe Subject: Re: [PATCH 1/3] arm64: ptrace: Add is_syscall_success to handle compat Message-ID: <20210416123322.GA23184@arm.com> References: <20210416075533.7720-1-zhe.he@windriver.com> MIME-Version: 1.0 In-Reply-To: <20210416075533.7720-1-zhe.he@windriver.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-loop: linux-audit@redhat.com X-Mailman-Approved-At: Fri, 16 Apr 2021 08:45:07 -0400 Cc: Mark Rutland , oleg@redhat.com, linux-kernel@vger.kernel.org, linux-audit@redhat.com, will@kernel.org, linux-arm-kernel@lists.infradead.org X-BeenThere: linux-audit@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: Linux Audit Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-audit-bounces@redhat.com Errors-To: linux-audit-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=linux-audit-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Fri, Apr 16, 2021 at 03:55:31PM +0800, He Zhe wrote: > The general version of is_syscall_success does not handle 32-bit > compatible case, which would cause 32-bit negative return code to be > recoganized as a positive number later and seen as a "success". > > Since is_compat_thread is defined in compat.h, implementing > is_syscall_success in ptrace.h would introduce build failure due to > recursive inclusion of some basic headers like mutex.h. We put the > implementation to ptrace.c > > Signed-off-by: He Zhe > --- > arch/arm64/include/asm/ptrace.h | 3 +++ > arch/arm64/kernel/ptrace.c | 10 ++++++++++ > 2 files changed, 13 insertions(+) > > diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h > index e58bca832dff..3c415e9e5d85 100644 > --- a/arch/arm64/include/asm/ptrace.h > +++ b/arch/arm64/include/asm/ptrace.h > @@ -328,6 +328,9 @@ static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc) > regs->regs[0] = rc; > } > > +extern inline int is_syscall_success(struct pt_regs *regs); > +#define is_syscall_success(regs) is_syscall_success(regs) > + > /** > * regs_get_kernel_argument() - get Nth function argument in kernel > * @regs: pt_regs of that context > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > index 170f42fd6101..3266201f8c60 100644 > --- a/arch/arm64/kernel/ptrace.c > +++ b/arch/arm64/kernel/ptrace.c > @@ -1909,3 +1909,13 @@ int valid_user_regs(struct user_pt_regs *regs, struct task_struct *task) > else > return valid_native_regs(regs); > } > + > +inline int is_syscall_success(struct pt_regs *regs) > +{ > + unsigned long val = regs->regs[0]; > + > + if (is_compat_thread(task_thread_info(current))) > + val = sign_extend64(val, 31); > + > + return !IS_ERR_VALUE(val); > +} It's better to use compat_user_mode(regs) here instead of is_compat_thread(). It saves us from worrying whether regs are for the current context. I think we should change regs_return_value() instead. This function seems to be called from several other places and it has the same potential problems if called on compat pt_regs. -- Catalin -- Linux-audit mailing list Linux-audit@redhat.com https://listman.redhat.com/mailman/listinfo/linux-audit