sys_personality: change sys_personality() to accept "unsigned int" instead of u_long
Oleg Nesterov [Fri, 4 Jun 2010 21:14:58 +0000 (14:14 -0700)]
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: Wenming Zhang <wezhang@redhat.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/personality.h
include/linux/syscalls.h
kernel/exec_domain.c

index 1261208..eec3bae 100644 (file)
@@ -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__ */
 
index a1a86a5..7f614ce 100644 (file)
@@ -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,
index c35452c..dd62f8e 100644 (file)
@@ -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)
 {
-       struct exec_domain *    ep;
-       u_long                  pers = personality(personality);
+       unsigned int pers = personality(personality);
+       struct exec_domain *ep;
 
        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;
 }