From 08d4a24659f1284f33e574211435aa12ce968477 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Thu, 13 Jan 2011 15:47:26 -0800 Subject: hugetlb: check the return value of string conversion in sysctl handler proc_doulongvec_minmax may fail if the given buffer doesn't represent a valid number. If we provide something invalid we will initialize the resulting value (nr_overcommit_huge_pages in this case) to a random value from the stack. The issue was introduced by a3d0c6aa when the default handler has been replaced by the helper function where we do not check the return value. Reproducer: echo "" > /proc/sys/vm/nr_overcommit_hugepages [akpm@linux-foundation.org: correctly propagate proc_doulongvec_minmax return code] Signed-off-by: Michal Hocko Cc: CAI Qian Cc: Nishanth Aravamudan Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) (limited to 'mm') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 8e31cda6fc2..363c4d22602 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1859,13 +1859,16 @@ static int hugetlb_sysctl_handler_common(bool obey_mempolicy, { struct hstate *h = &default_hstate; unsigned long tmp; + int ret; if (!write) tmp = h->max_huge_pages; table->data = &tmp; table->maxlen = sizeof(unsigned long); - proc_doulongvec_minmax(table, write, buffer, length, ppos); + ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); + if (ret) + goto out; if (write) { NODEMASK_ALLOC(nodemask_t, nodes_allowed, @@ -1880,8 +1883,8 @@ static int hugetlb_sysctl_handler_common(bool obey_mempolicy, if (nodes_allowed != &node_states[N_HIGH_MEMORY]) NODEMASK_FREE(nodes_allowed); } - - return 0; +out: + return ret; } int hugetlb_sysctl_handler(struct ctl_table *table, int write, @@ -1919,21 +1922,24 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write, { struct hstate *h = &default_hstate; unsigned long tmp; + int ret; if (!write) tmp = h->nr_overcommit_huge_pages; table->data = &tmp; table->maxlen = sizeof(unsigned long); - proc_doulongvec_minmax(table, write, buffer, length, ppos); + ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); + if (ret) + goto out; if (write) { spin_lock(&hugetlb_lock); h->nr_overcommit_huge_pages = tmp; spin_unlock(&hugetlb_lock); } - - return 0; +out: + return ret; } #endif /* CONFIG_SYSCTL */ -- cgit v1.2.3-70-g09d2