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SubjectRe: [PATCH] fix sys_prctl() returned uninitialized value
Quoting Andrew Morton (akpm@linux-foundation.org):
> On Wed, 21 May 2008 22:01:17 -0700 "Andrew G. Morgan" <morgan@kernel.org> wrote:
>
> > this is the default expected by the subsequent switch ().
> >
> > Signed-off-by: Andrew G. Morgan <morgan@kernel.org>
> > ---
> > 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)) {
>
> Looking at it some more there are two cases which don't initialise
> `error': PR_SET_PDEATHSIG and PR_SET_DUMPABLE. (let's set aside the
> silliness of having sys_prctl() perform set_dumpable()'s argument
> checking for it).

Hmm, I don't know what kernel version I was looking at, or whose glasses
I was wearing at the time. Clearly these are the two...

> So I would propose this fix, mainly because it removes that nasty
> uninitialized_var(). Please review carefully.
>
>
>
> From: Shi Weihua <shiwh@cn.fujitsu.com>
>
> If none of the switch cases match, the PR_SET_PDEATHSIG and
> PR_SET_DUMPABLE cases of the switch statement will never write to local
> variable `error'.
>
> Signed-off-by: Shi Weihua <shiwh@cn.fujitsu.com>
> Cc: Andrew G. Morgan <morgan@kernel.org>
> Cc: "Serge E. Hallyn" <serue@us.ibm.com>

Acked-by: Serge Hallyn <serue@us.ibm.com>

> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>
> kernel/sys.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff -puN kernel/sys.c~sys_prctl-fix-return-of-uninitialized-value kernel/sys.c
> --- a/kernel/sys.c~sys_prctl-fix-return-of-uninitialized-value
> +++ a/kernel/sys.c
> @@ -1652,7 +1652,7 @@ asmlinkage long sys_umask(int mask)
> asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
> unsigned long arg4, unsigned long arg5)
> {
> - long uninitialized_var(error);
> + long error = 0;
>
> if (security_task_prctl(option, arg2, arg3, arg4, arg5, &error))
> return error;
> @@ -1701,9 +1701,7 @@ asmlinkage long sys_prctl(int option, un
> error = PR_TIMING_STATISTICAL;
> break;
> case PR_SET_TIMING:
> - if (arg2 == PR_TIMING_STATISTICAL)
> - error = 0;
> - else
> + if (arg2 != PR_TIMING_STATISTICAL)
> error = -EINVAL;
> break;
>
> _


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