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    Subject[PATCH 5.10 056/221] ia64: fix ptrace(PTRACE_SYSCALL_INFO_EXIT) sign
    Date
    From: Sergei Trofimovich <slyfox@gentoo.org>

    [ 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@gentoo.org
    Link: https://bugs.gentoo.org/769614
    Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
    Reported-by: Dmitry V. Levin <ldv@altlinux.org>
    Reviewed-by: Dmitry V. Levin <ldv@altlinux.org>
    Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 6c6f16e409a8..0d23c0049301 100644
    --- a/arch/ia64/include/asm/syscall.h
    +++ b/arch/ia64/include/asm/syscall.h
    @@ -32,7 +32,7 @@ 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


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