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authorHan Pingtian <hanpt@linux.vnet.ibm.com>2014-01-23 15:53:17 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-23 16:36:52 -0800
commitda8c757b080ee84f219fa2368cb5dd23ac304fc0 (patch)
treec6a351683151f272a488e0fc379653a1b259e64f
parentcc81717ed3bc6d4f3738d13a1e097437caada0e9 (diff)
mm: prevent setting of a value less than 0 to min_free_kbytes
If echo -1 > /proc/vm/sys/min_free_kbytes, the system will hang. Changing proc_dointvec() to proc_dointvec_minmax() in the min_free_kbytes_sysctl_handler() can prevent this to happen. mhocko said: : You can still do echo $BIG_VALUE > /proc/vm/sys/min_free_kbytes and make : your machine unusable but I agree that proc_dointvec_minmax is more : suitable here as we already have: : : .proc_handler = min_free_kbytes_sysctl_handler, : .extra1 = &zero, : : It used to work properly but then 6fce56ec91b5 ("sysctl: Remove references : to ctl_name and strategy from the generic sysctl table") has removed : sysctl_intvec strategy and so extra1 is ignored. Signed-off-by: Han Pingtian <hanpt@linux.vnet.ibm.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page_alloc.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f18f016cca80..a818d568ddf3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5754,7 +5754,12 @@ module_init(init_per_zone_wmark_min)
int min_free_kbytes_sysctl_handler(ctl_table *table, int write,
void __user *buffer, size_t *length, loff_t *ppos)
{
- proc_dointvec(table, write, buffer, length, ppos);
+ int rc;
+
+ rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
+ if (rc)
+ return rc;
+
if (write) {
user_min_free_kbytes = min_free_kbytes;
setup_per_zone_wmarks();

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