linux-kernel - [PATCH 3/3] audit: Use syscall_get_return_value to get syscall return code in audit_syscall

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Date:   Fri, 16 Apr 2021 15:55:33 +0800
From:   He Zhe <zhe.he@...driver.com>
To:     oleg@...hat.com, catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, paul@...l-moore.com,
        eparis@...hat.com, linux-audit@...hat.com,
        linux-kernel@...r.kernel.org, zhe.he@...driver.com
Subject: [PATCH 3/3] audit: Use syscall_get_return_value to get syscall return code in audit_syscall_exit

regs_return_value for some architectures like arm64 simply retrieve
register value from pt_regs without sign extension in 32-bit compatible
case and cause audit to have false syscall return code. For example,
32-bit -13 would be treated as 4294967283 below.

type=SYSCALL msg=audit(1611110715.887:582): arch=40000028 syscall=322
success=yes exit=4294967283

We just added proper sign extension in syscall_get_return_value which
should be used instead.

Signed-off-by: He Zhe <zhe.he@...driver.com>
---
 include/linux/audit.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 82b7c1116a85..135adbe22c19 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -334,7 +334,7 @@ static inline void audit_syscall_exit(void *pt_regs)
 {
 	if (unlikely(audit_context())) {
 		int success = is_syscall_success(pt_regs);
-		long return_code = regs_return_value(pt_regs);
+		long return_code = syscall_get_return_value(current, pt_regs);
 
 		__audit_syscall_exit(success, return_code);
 	}
-- 
2.17.1