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| author |   Oleg Nesterov <oleg@tv-sign.ru> | 2008-04-30 00:54:28 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-30 08:29:49 -0700 |
| commit | 1dd768c0815334d2319d6377f0750ace075b6142 (patch) | |
| tree | 13e3d42f3679ef1a50e276abdbeafccc9cfe1ed0 /kernel | |
| parent | pids: __set_special_pids: use change_pid() helper (diff) | |
| download | linux-dev-1dd768c0815334d2319d6377f0750ace075b6142.tar.xz linux-dev-1dd768c0815334d2319d6377f0750ace075b6142.zip | |
pids: sys_getsid: fix unsafe *pid usage, fix possible 0 instead of -ESRCH
1. sys_getsid() needs rcu_read_lock() to derive the session _nr, even if
the task is current, otherwise we can race with another thread which
does sys_setsid().
2. The task can exit between find_task_by_vpid() and task_session_vnr(),
in that unlikely case sys_getsid() returns 0 instead of -ESRCH.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sys.c | 33 |
1 files changed, 20 insertions, 13 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index 5d0b44cd435c..ddd28e261f3a 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1022,23 +1022,30 @@ asmlinkage long sys_getpgrp(void) asmlinkage long sys_getsid(pid_t pid) { + struct task_struct *p; + struct pid *sid; + int retval; + + rcu_read_lock(); if (!pid) - return task_session_vnr(current); + sid = task_session(current); else { - int retval; - struct task_struct *p; - - rcu_read_lock(); - p = find_task_by_vpid(pid); retval = -ESRCH; - if (p) { - retval = security_task_getsid(p); - if (!retval) - retval = task_session_vnr(p); - } - rcu_read_unlock(); - return retval; + p = find_task_by_vpid(pid); + if (!p) + goto out; + sid = task_session(p); + if (!sid) + goto out; + + retval = security_task_getsid(p); + if (retval) + goto out; } + retval = pid_vnr(sid); +out: + rcu_read_unlock(); + return retval; } asmlinkage long sys_setsid(void) |