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authorArnd Bergmann <arnd@arndb.de>2010-02-27 19:49:37 +0100
committerFrederic Weisbecker <fweisbec@gmail.com>2010-04-10 15:34:21 +0200
commit5534ecb2dda04345e8243901e0e49599228b4273 (patch)
tree1d09ca0bcc6fcac12310300a306c233e350151c7 /kernel/ptrace.c
parent2eaa9cfdf33b8d7fb7aff27792192e0019ae8fc6 (diff)
downloadlinux-2.6.34-ux500-5534ecb2dda04345e8243901e0e49599228b4273.tar.gz
ptrace: kill BKL in ptrace syscall
The comment suggests that this usage is stale. There is no bkl in the exec path so if there is a race lurking there, the bkl in ptrace is not going to help in this regard. Overview of the possibility of "accidental" races this bkl might protect: - ptrace_traceme() is protected against task removal and concurrent read/write on current->ptrace as it locks write tasklist_lock. - arch_ptrace_attach() is serialized by ptrace_traceme() against concurrent PTRACE_TRACEME or PTRACE_ATTACH - ptrace_attach() is protected the same way ptrace_traceme() and in turn serializes arch_ptrace_attach() - ptrace_check_attach() does its own well described serializing too. There is no obvious race here. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Roland McGrath <roland@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Roland McGrath <roland@redhat.com>
Diffstat (limited to 'kernel/ptrace.c')
-rw-r--r--kernel/ptrace.c10
1 files changed, 0 insertions, 10 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 42ad8ae729a..53575020f82 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -666,10 +666,6 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
struct task_struct *child;
long ret;
- /*
- * This lock_kernel fixes a subtle race with suid exec
- */
- lock_kernel();
if (request == PTRACE_TRACEME) {
ret = ptrace_traceme();
if (!ret)
@@ -703,7 +699,6 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
out_put_task_struct:
put_task_struct(child);
out:
- unlock_kernel();
return ret;
}
@@ -813,10 +808,6 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
struct task_struct *child;
long ret;
- /*
- * This lock_kernel fixes a subtle race with suid exec
- */
- lock_kernel();
if (request == PTRACE_TRACEME) {
ret = ptrace_traceme();
goto out;
@@ -846,7 +837,6 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
out_put_task_struct:
put_task_struct(child);
out:
- unlock_kernel();
return ret;
}
#endif /* CONFIG_COMPAT */