Messages in this thread | | | Date | Fri, 16 Apr 2021 13:33:22 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH 1/3] arm64: ptrace: Add is_syscall_success to handle compat |
| |
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 <zhe.he@windriver.com> > --- > 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
| |