[PATCH AUTOSEL 4.19 23/23] ia64: fix ptrace(PTRACE_SYSCALL_INFO_EXIT) sign

From: Sasha Levin
Date: Tue Mar 16 2021 - 21:04:39 EST


From: Sergei Trofimovich <slyfox@xxxxxxxxxx>

[ Upstream commit 61bf318eac2c13356f7bd1c6a05421ef504ccc8a ]

In https://bugs.gentoo.org/769614 Dmitry noticed that
`ptrace(PTRACE_GET_SYSCALL_INFO)` does not return error sign properly.

The bug is in mismatch between get/set errors:

static inline long syscall_get_error(struct task_struct *task,
struct pt_regs *regs)
{
return regs->r10 == -1 ? regs->r8:0;
}

static inline long syscall_get_return_value(struct task_struct *task,
struct pt_regs *regs)
{
return regs->r8;
}

static inline void syscall_set_return_value(struct task_struct *task,
struct pt_regs *regs,
int error, long val)
{
if (error) {
/* error < 0, but ia64 uses > 0 return value */
regs->r8 = -error;
regs->r10 = -1;
} else {
regs->r8 = val;
regs->r10 = 0;
}
}

Tested on v5.10 on rx3600 machine (ia64 9040 CPU).

Link: https://lkml.kernel.org/r/20210221002554.333076-2-slyfox@xxxxxxxxxx
Link: https://bugs.gentoo.org/769614
Signed-off-by: Sergei Trofimovich <slyfox@xxxxxxxxxx>
Reported-by: Dmitry V. Levin <ldv@xxxxxxxxxxxx>
Reviewed-by: Dmitry V. Levin <ldv@xxxxxxxxxxxx>
Cc: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/ia64/include/asm/syscall.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/ia64/include/asm/syscall.h b/arch/ia64/include/asm/syscall.h
index 1d0b875fec44..ec909eec0b4c 100644
--- a/arch/ia64/include/asm/syscall.h
+++ b/arch/ia64/include/asm/syscall.h
@@ -35,7 +35,7 @@ static inline void syscall_rollback(struct task_struct *task,
static inline long syscall_get_error(struct task_struct *task,
struct pt_regs *regs)
{
- return regs->r10 == -1 ? regs->r8:0;
+ return regs->r10 == -1 ? -regs->r8:0;
}

static inline long syscall_get_return_value(struct task_struct *task,
--
2.30.1