From 60aa0fa94c00942cc2c9f67f05d4a0d9e15349c7 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Thu, 3 Sep 2009 19:21:45 +0200 Subject: [PATCH] sys_setrlimit: make sure ->rlim_max never grows References: FATE#305733 Patch-mainline: no (later) Mostly preparation for Jiri's changes, but probably makes sense anyway. sys_setrlimit() checks new_rlim.rlim_max <= old_rlim->rlim_max, but when it takes task_lock() old_rlim->rlim_max can be already lowered. Move this check under task_lock(). Currently this is not important, we can only race with our sub-thread, this means the application is stupid. But when we change the code to allow the update of !current task's limits, it becomes important to make sure ->rlim_max can be lowered "reliably" even if we race with the application doing sys_setrlimit(). Signed-off-by: Oleg Nesterov Signed-off-by: Jiri Slaby --- kernel/sys.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1313,10 +1313,6 @@ SYSCALL_DEFINE2(setrlimit, unsigned int, return -EFAULT; if (new_rlim.rlim_cur > new_rlim.rlim_max) return -EINVAL; - old_rlim = current->signal->rlim + resource; - if ((new_rlim.rlim_max > old_rlim->rlim_max) && - !capable(CAP_SYS_RESOURCE)) - return -EPERM; if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > sysctl_nr_open) return -EPERM; @@ -1334,11 +1330,16 @@ SYSCALL_DEFINE2(setrlimit, unsigned int, new_rlim.rlim_cur = 1; } + old_rlim = current->signal->rlim + resource; task_lock(current->group_leader); - *old_rlim = new_rlim; + if ((new_rlim.rlim_max <= old_rlim->rlim_max) || + capable(CAP_SYS_RESOURCE)) + *old_rlim = new_rlim; + else + retval = -EPERM; task_unlock(current->group_leader); - if (resource != RLIMIT_CPU) + if (retval || resource != RLIMIT_CPU) goto out; /* @@ -1352,7 +1353,7 @@ SYSCALL_DEFINE2(setrlimit, unsigned int, update_rlimit_cpu(current, new_rlim.rlim_cur); out: - return 0; + return retval; } /*