Re: [PATCH] Increase judgment on buf.

[Paul Eggert <eggert@cs.ucla.edu>]

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On 2023-05-20 03:19, Xi Ruoyao via Libc-alpha wrote:
> If a LTP test relies on a EFAULT here, then LTP has a bug.  You should
> tell LTP to fix it then.

LTP fstat03 allows either EFAULT or SIGSEGV, but no other behavior, when 
'stat' is passed a null pointer.

Therefore that test is too strict for POSIX, as the POSIX behavior is 
undefined.

It's also too strict for GNU/Linux, because it insists on SIGSEGV 
whereas any terminating signal will do (e.g., SIGABRT).

Proposed LTP patch attached.

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From 8a2b3f75d2b61e5e4ec0a2c93f3db62584daf1cd Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 21 May 2023 01:15:40 -0700
Subject: [PATCH] fstat03 wrongly required SIGSEGV

Change fstat03 to allow the syscall to signal SIGABRT (or any other
signal) instead of SIGSEGV when a null pointer is passed, as POSIX
says behavior is undefined and the glibc behavior (which is a bit
better defined) could be any signal, not necessarily SIGSEGV.

Signed-off-by: Paul Eggert <eggert@cs.ucla.edu>
---
 testcases/kernel/syscalls/fstat/fstat03.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/testcases/kernel/syscalls/fstat/fstat03.c b/testcases/kernel/syscalls/fstat/fstat03.c
index 4ff37e882..a400692e9 100644
--- a/testcases/kernel/syscalls/fstat/fstat03.c
+++ b/testcases/kernel/syscalls/fstat/fstat03.c
@@ -10,7 +10,7 @@
  * 1) Calls fstat() with closed file descriptor
  *    -> EBADF
  * 2) Calls fstat() with an invalid address for stat structure
- *    -> EFAULT (or receive signal SIGSEGV)
+ *    -> EFAULT (or receive signal)
  */
 
 #include <errno.h>
@@ -70,8 +70,8 @@ static void run(unsigned int tc_num)
 	}
 	SAFE_WAITPID(pid, &status, 0);
 
-	if (tcases[tc_num].exp_err == EFAULT && WTERMSIG(status) == SIGSEGV) {
-		tst_res(TPASS, "fstat() failed as expected with SIGSEGV");
+	if (tcases[tc_num].exp_err == EFAULT && WIFSIGNALED(status)) {
+		tst_res(TPASS, "fstat() failed as expected with a signal");
 		return;
 	}
 
-- 
2.39.2