Re: [PATCH] fix sys_prctl() returned uninitialized value

[Andrew G. Morgan]

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Looks like I goofed here. :*(

Andrew Morton wrote:
| Oh dear, there are so many things wrong with this...
|
| - if security_task_prctl() is returning "fail" then why on earth
|   isn't it setting the error code?

Its not failing, as Shi points out in their patch preamble, its simply
passing-through - security_task_prctl() doesn't implement the requested
PR_* code, so it expects something else (sys_prctl() proper) to set this
value.

| - cap_task_prctl() _does_ set `error' is if returns non-zero, so it
|   must be one of the other myriad backend implementations of
|   security_task_prctl() which is busted.  Which one is it?

None of them. In this case, none of the security modules implement the
requested PRCTL.

| - With the above patch applied, sys_prctl() will return zero (ie:
|   "success") even though it just failed.

Not sure what you mean here. The switch statement only sets a non-zero
value for error on a failing path. It assumes that the error value is
initially zero.

| - Can't we remove the sixth argument to security_task_prctl() and
|   just return the result code like a sane function would do?

A bunch of capability related prctl()s will cease to work.

I'd prefer the attached patch, but I don't object to Shi's. In which case:

~   Acked-by: Andrew G. Morgan <morgan@xxxxxxxxxx>

Cheers

Andrew

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From 5064e50b4a10cef2fe48a5716ffb3845488f0a14 Mon Sep 17 00:00:00 2001
From: Andrew G. Morgan <morgan@xxxxxxxxxx>
Date: Wed, 21 May 2008 21:46:35 -0700
Subject: [PATCH] Bug fix: default error to success

this is the default expected by the subsequent switch ().

Signed-off-by: Andrew G. Morgan <morgan@xxxxxxxxxx>
---
 kernel/sys.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index 895d2d4..cb25a64 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1657,6 +1657,8 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
 	if (security_task_prctl(option, arg2, arg3, arg4, arg5, &error))
 		return error;
 
+	error = 0;
+
 	switch (option) {
 		case PR_SET_PDEATHSIG:
 			if (!valid_signal(arg2)) {
-- 
1.5.3.7