From: He Zhe <zhe.he@windriver.com>
To: oleg@redhat.com, catalin.marinas@arm.com, will@kernel.org,
linux-arm-kernel@lists.infradead.org, paul@paul-moore.com,
eparis@redhat.com, linux-audit@redhat.com,
linux-kernel@vger.kernel.org, zhe.he@windriver.com
Subject: [PATCH v2 2/3] arm64: syscall.h: Add sign extension handling in syscall_get_return_value for compat
Date: Fri, 23 Apr 2021 18:35:32 +0800 [thread overview]
Message-ID: <20210423103533.30121-2-zhe.he@windriver.com> (raw)
In-Reply-To: <20210423103533.30121-1-zhe.he@windriver.com>
Add sign extension handling in syscall_get_return_value so that it can
handle 32-bit compatible case and can be used by for example audit, just
like what syscall_get_error does.
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: He Zhe <zhe.he@windriver.com>
---
v1 to v2: Improve error code check suggested by Mark
arch/arm64/include/asm/syscall.h | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index cfc0672013f6..c3b5fca82ff4 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -44,7 +44,20 @@ static inline long syscall_get_error(struct task_struct *task,
static inline long syscall_get_return_value(struct task_struct *task,
struct pt_regs *regs)
{
- return regs->regs[0];
+ long val = regs->regs[0];
+ long error = val;
+
+ if (compat_user_mode(regs))
+ error = sign_extend64(error, 31);
+
+ /*
+ * Return codes with bit 31 set may or may not be an error code.
+ * For example, mmap may return a legal 32 bit address with bit 31 set
+ * for 32 bit thread, in which case the untouched val should be
+ * returned. Otherwise, the sign-extended error should be returned if
+ * it still falls in error number range.
+ */
+ return IS_ERR_VALUE(error) ? error : val;
}
static inline void syscall_set_return_value(struct task_struct *task,
--
2.17.1
next prev parent reply other threads:[~2021-04-23 10:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-23 10:35 [PATCH v2 1/3] arm64: ptrace: Add is_syscall_success to handle compat He Zhe
2021-04-23 10:35 ` He Zhe [this message]
2021-05-05 17:30 ` [PATCH v2 2/3] arm64: syscall.h: Add sign extension handling in syscall_get_return_value for compat Mark Rutland
2021-04-23 10:35 ` [PATCH v2 3/3] audit: Use syscall_get_return_value to get syscall return code in audit_syscall_exit He Zhe
2021-04-24 5:44 ` kernel test robot
2021-04-26 9:16 ` [PATCH] alpha: Add syscall_get_return_value() He Zhe
2021-04-26 9:21 ` He Zhe
2021-05-10 22:38 ` [PATCH v2 3/3] audit: Use syscall_get_return_value to get syscall return code in audit_syscall_exit Paul Moore
2021-05-11 3:19 ` He Zhe
2021-05-11 14:51 ` Paul Moore
2021-05-12 8:43 ` He Zhe
2021-05-14 20:33 ` Paul Moore
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