Commit 485d5276 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

sys_personality: change sys_personality() to accept "unsigned int" instead of u_long 



task_struct->pesonality is "unsigned int", but sys_personality() paths use
"unsigned long pesonality".  This means that every assignment or
comparison is not right.  In particular, if this argument does not fit
into "unsigned int" __set_personality() changes the caller's personality
and then sys_personality() returns -EINVAL.

Turn this argument into "unsigned int" and avoid overflows.  Obviously,
this is the user-visible change, we just ignore the upper bits.  But this
can't break the sane application.

There is another thing which can confuse the poorly written applications.
User-space thinks that this syscall returns int, not long.  This means
that the returned value can be negative and look like the error code.  But
note that libc won't be confused and thus errno won't be set, and with
this patch the user-space can never get -1 unless sys_personality() really
fails.  And, most importantly, the negative RET != -1 is only possible if
that app previously called personality(RET).

Pointed-out-by: default avatarWenming Zhang <wezhang@redhat.com>
Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d6d03f91

include/linux/personality.h

+1 −1
Original line number Diff line number Diff line
@@ -12,7 +12,7 @@ struct pt_regs; 


extern int		register_exec_domain(struct exec_domain *);

extern int		unregister_exec_domain(struct exec_domain *);

extern int		__set_personality(unsigned long);

extern int		__set_personality(unsigned int);



#endif /* __KERNEL__ */

include/linux/syscalls.h

+1 −1
Original line number Diff line number Diff line
@@ -289,7 +289,7 @@ asmlinkage long sys_capget(cap_user_header_t header, 
				cap_user_data_t dataptr);

asmlinkage long sys_capset(cap_user_header_t header,

				const cap_user_data_t data);

asmlinkage long sys_personality(u_long personality);

asmlinkage long sys_personality(unsigned int personality);



asmlinkage long sys_sigpending(old_sigset_t __user *set);

asmlinkage long sys_sigprocmask(int how, old_sigset_t __user *set,

kernel/exec_domain.c

+9 −9
Original line number Diff line number Diff line
@@ -27,7 +27,7 @@ static struct exec_domain *exec_domains = &default_exec_domain; 
static DEFINE_RWLOCK(exec_domains_lock);





static u_long ident_map[32] = {

static unsigned long ident_map[32] = {

	0,	1,	2,	3,	4,	5,	6,	7,

	8,	9,	10,	11,	12,	13,	14,	15,

	16,	17,	18,	19,	20,	21,	22,	23,
@@ -56,10 +56,10 @@ default_handler(int segment, struct pt_regs *regp) 
}



static struct exec_domain *

lookup_exec_domain(u_long personality)

lookup_exec_domain(unsigned int personality)

{

	unsigned int pers = personality(personality);

	struct exec_domain *ep;

	u_long			pers = personality(personality);



	read_lock(&exec_domains_lock);

	for (ep = exec_domains; ep; ep = ep->next) {
@@ -70,7 +70,7 @@ lookup_exec_domain(u_long personality) 


#ifdef CONFIG_MODULES

	read_unlock(&exec_domains_lock);

	request_module("personality-%ld", pers);

	request_module("personality-%d", pers);

	read_lock(&exec_domains_lock);



	for (ep = exec_domains; ep; ep = ep->next) {
@@ -135,7 +135,7 @@ unregister: 
}



int

__set_personality(u_long personality)

__set_personality(unsigned int personality)

{

	struct exec_domain	*ep, *oep;
@@ -188,9 +188,9 @@ static int __init proc_execdomains_init(void) 
module_init(proc_execdomains_init);

#endif



SYSCALL_DEFINE1(personality, u_long, personality)

SYSCALL_DEFINE1(personality, unsigned int, personality)

{

	u_long old = current->personality;

	unsigned int old = current->personality;



	if (personality != 0xffffffff) {

		set_personality(personality);
@@ -198,7 +198,7 @@ SYSCALL_DEFINE1(personality, u_long, personality) 
			return -EINVAL;

	}



	return (long)old;

	return old;

}

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