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| author | Arnd Bergmann <arnd@arndb.de> | 2010-02-27 19:49:37 +0100 |
|---|---|---|
| committer | Frederic Weisbecker <fweisbec@gmail.com> | 2010-04-10 15:34:21 +0200 |
| commit | 5534ecb2dda04345e8243901e0e49599228b4273 (patch) | |
| tree | 1d09ca0bcc6fcac12310300a306c233e350151c7 /kernel/ptrace.c | |
| parent | 2eaa9cfdf33b8d7fb7aff27792192e0019ae8fc6 (diff) | |
| download | linux-stable-5534ecb2dda04345e8243901e0e49599228b4273.tar.gz linux-stable-5534ecb2dda04345e8243901e0e49599228b4273.tar.bz2 linux-stable-5534ecb2dda04345e8243901e0e49599228b4273.zip | |
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.c | 10 |
1 files changed, 0 insertions, 10 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 42ad8ae729a0..53575020f82b 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 */ |