The patch titled pids: sys_getpgid: fix unsafe *pid usage, s/tasklist/rcu/ has been removed from the -mm tree. Its filename was pids-sys_getpgid-fix-unsafe-pid-usage-s-tasklist-rcu.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: pids: sys_getpgid: fix unsafe *pid usage, s/tasklist/rcu/ From: Oleg Nesterov <oleg@xxxxxxxxxx> 1. sys_getpgid() needs rcu_read_lock() to derive the pgrp _nr, even if the task is current, otherwise we can race with another thread which does sys_setpgid(). 2. Use rcu_read_lock() instead of tasklist_lock when pid != 0, make sure that we don't use the NULL pid if the task exits right after successful find_task_by_vpid(). Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Roland McGrath <roland@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/sys.c | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff -puN kernel/sys.c~pids-sys_getpgid-fix-unsafe-pid-usage-s-tasklist-rcu kernel/sys.c --- a/kernel/sys.c~pids-sys_getpgid-fix-unsafe-pid-usage-s-tasklist-rcu +++ a/kernel/sys.c @@ -991,31 +991,37 @@ out: asmlinkage long sys_getpgid(pid_t pid) { + struct task_struct *p; + struct pid *grp; + int retval; + + rcu_read_lock(); if (!pid) - return task_pgrp_vnr(current); + grp = task_pgrp(current); else { - int retval; - struct task_struct *p; - - read_lock(&tasklist_lock); - p = find_task_by_vpid(pid); retval = -ESRCH; - if (p) { - retval = security_task_getpgid(p); - if (!retval) - retval = task_pgrp_vnr(p); - } - read_unlock(&tasklist_lock); - return retval; + p = find_task_by_vpid(pid); + if (!p) + goto out; + grp = task_pgrp(p); + if (!grp) + goto out; + + retval = security_task_getpgid(p); + if (retval) + goto out; } + retval = pid_vnr(grp); +out: + rcu_read_unlock(); + return retval; } #ifdef __ARCH_WANT_SYS_GETPGRP asmlinkage long sys_getpgrp(void) { - /* SMP - assuming writes are word atomic this is fine */ - return task_pgrp_vnr(current); + return sys_getpgid(0); } #endif _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are origin.patch posix-timers-bug-10460-discard-the-pending-signal-when-the-timer-is-destroyed.patch workqueue-remove-redundant-function-invocation.patch put_pid-make-sure-we-dont-free-the-live-pid.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html